Comparative Biochemistry and Physiology Part C Comparative Pharmacology

Published by Elsevier
Print ISSN: 0306-4492
1. In the livers of Salmo gairdneri specimens exposed to sublethal concentrations of un-ionized ammonia (UIA), changes were seen to occur in the properties of fructose 1,6-bisphosphatase along with an increase in total proteolytic activity and free aminoacid concentration.2. The increase in environmental pH leads to similar though less marked effects.3. In line with the studies carried out by other workers, the changes observed in this gluconeogenic enzyme are believed to be brought about by lysosomal proteases, which may be assigned the value of indicators of environmental stress.
1. Platelet monoamine oxidase (MAO) activity in Macaca Mulatta tended to increase with age (r = 0.41, P < 0.01) in males, but not in females; no mean difference between males and females was observed.2. MAO activities were closely correlated when two different substrates for the enzyme, tryptamine and benzylamine, were compared (r = 0.82, P < 0.01).3. A predominant influence of genetic factors on platelet MAO activity was suggested by a significantly higher intraclass correlation for half-sib pairs compared to non-related, age and sex-matched pairs.4. Significant differences were also observed for platelet MAO activity comparisons between 4 primate species: Macaca mulatta, Macaca arctoides, Cercopithecus aethiops and Homo sapiens.
1. Trout (Salvelinus fontinalis) were fed PCB (Aroclor 1254) or 3-methylcholanthrene over and 18-day or a 25-day period, respectively, and the induction of hepatic MFO enzymes was studied.2. Trout fed PCB to produce tissue concentrations of about 39 ppm showed a significant increase in the activity of ethoxycoumarin O-de-ethylase, and slight but non-significant increases in the activity of aniline hydroxylase, and in cytochrome P-450 and microsomal protein concentrations.3. Trout fed 9 doses of 0.35 mg 3-methylcholanthrene showed significant increases in the activity of ethoxycoumarin O-de-ethylase, aniline hydroxylase, aldrin epoxidase and in concentrations of cytochrome P-450 and microsomal protein.
[125Sb]sodium stibogluconate was accumulated by Leishmania parasites in vitro to much higher concentrations overall than that in their surroundings and could not be readily washed out. 2. The distribution ratio between parasites and their suspending medium varied from 10 to 36 for amastigotes and from 2 to 14 for promastigotes. 3. Treatment with glutaraldehyde did not decrease the amount accumulated. 4. The findings suggest that the drug is bound to the parasite and support the hypothesis that the toxic effect of sodium stibogluconate on the parasite is not a direct one.
1. In a total of fifty ground squirrel (Spermophilus tridecemlineauts) hearts studied, there was a significant increase in adrenergic catecholamine histofluorescnece in the winter hibernating state compared to the winter non-hibernating state.2. There was a ssignificant increase in total cardiac noreppinephrine content in winter hibernation 0.44 ± 0.08 μg/g compared to winter non-hibernating 0.27 ±0.06 μg/g, P = <0.001.3. The cardiac adrenergic to histofuorescence intensity was similar for natural hibernation and summer induced hibernation.4. The variations in specific distribution and intensity of adrenergic histofluorescence throughout all areas of the heart is described for natural winter hibernation and non-hibernation, as well as summer induced hibernation and activity.
1. DMBA, a chemical carcinogen, was topically applied to skin patches of hibernating and nonhibernating ground squirrels (Spermophilus tridecemlineatus). 2. Macroscopically, hyperpigmentation, hair loss and excessive skin sloughing were evident in all treated nonhibernator skin patches. 3. Histological sections of skin revealed hyperkeratosis, epidermal vesicles, acanthosis, an indistinct basal layer and increased vascularization in nonhibernators. 4. Skin patches on hibernators were unaffected by treatment showing hibernation confers protection from the pathological effects of DMBA.
1.1. The time-course of choline uptake by P. varians ventral cord has two linear phases and then curves off.2.2. Phase 1 has a Q10 of 1.48, is not abolished at 0–4°C, is not saturable, and is not inhibited by hemicholinium-3 or replacement of sodium in the medium. However, alteration of the external potassium concentration modifies phase 1.3.3. Phase 2 has a Q10 of 1.98, is saturable, is dependent on the presence of sodium in the medium, is inhibited competitively by hemicholinium-3, and is almost abolished at 0–4°C. Kinetic analysis indicates that uptake in phase 2 is due to both high- and low-affinity choline carriers with Km values of 3.3 and 64.9 μM, respectively.4.4. Phase 1 probably represents a non-mediated process and phase 2 is due to a choline carrier system similar to, but not the same as, that found in nervous tissues of other animals.
1. Radioassay of p-nitroanisole O-demethylation in liver homogenates and/or microsomes is described. Disappearance of as little as five nanomoles substrate can be precisely determined.2. O-Demethylation rates from radioassays and from spectroassays of formaldehyde correspond, but both are greater than apparent rates of p-nitrophenol production measured by spectrophotometry.3. Comparative studies were performed using homogenates and microsomes from vertebrates (9 species) and invertebrates (4 species). Results indicated species differences, enzyme induction and characteristic tissue levels of O-demethylation activity.4. Cost/time considerations favor the radioassay over usual spectrophotometric procedures for comparative studies involving large numbers of samples.
1.1. In Palaemonetes varians (Leach, 1814) the LCt50 for DFP, para-oxon and Soman was 280×10−4, 5·78×10−4 and 0·66×10−4 (M × min), respectively.2.2. After injection of a lethal dose of para-oxon a period of increased (convulsive) activity was followed by paralysis.3.3. The scaphognathite movements ceased rapidly after the injection. Cardiac arrest ensued after a considerable period of time. Cardiac arrest was not caused by a direct effect of the cholinesterase inhibitor but was secondary to the arrest of the scaphognathite movements.
1. Crude and fractioned homogenates of the midgut gland of Aplysia brasiliana were tested on the heart of the toad Bufo ictericus ictericus and cholinoceptive structures of some invertebrates.2. In the in situ heart of the toad the fractions, with increasing concentrations, first decreased both the frequency and the amplitude and then stopped the organ in diastole.3. On recovery from the effect of the fractions, the toad heart could not be stopped by vagus stimulation. This result is admitted as due to the urocanylcholine present in the fractions.4. The application of acetylcholine on an isolated toad heart previously treated by the active fractions was also ineffective. Atropine blocked the action of the active fractions in the isolated heart.5. The tonus and the frequency of beating of the isolated heart of A. brasiliana are enhanced by the active fractions. This action can be blocked by atropine but not by B.O.L. The quiescent isolated heart of this gastropod resumes its beating on the application of the active fractions.6. In the isolated heart of the bivalve Perna perna the active fractions also rise the amplitude of the beating.7. Crude homogenates and the active fractions of the midgut gland strongly contract the protractor muscle of the sea urchin lantern and the longitudinal muscle of the sea cucumber. In both cases this action can be blocked by atropine.8. Column muscle preparations of the sea anemone Bunodosoma caissarum are also sensitive to the active fractions.9. The present results confirm and extend to A. brasiliana the existence of cholinergic principles in the midgut gland, probably acetylcholine and urocanylcholine, as found by Blankenship et al. (1975) in another sea here.
1.1. The effects of acclimation to 300 and 940 milliosmole seawater and an acute hypo-osmotic stress on the weight-specific oxygen consumption of the gills, muscle and hepatopancreas of the blue crab. Callinectes sapidus, were determined.2.2. The gill and muscle tissues exhibited an increase in oxygen consumption on acclimation of crabs to a low salinity or when the tissues were subjected to an acute hypo-osmotic stress. Similar treatments did not alter the oxygen consumption of the hepatopancreas.3.3. At a concentration of 5 × 10−3 M, pentachlorophenol (PCP) and 2,4-dinitrophenol (DNP) caused inhibition of oxygen consumption in the tissues examined. The extent of this inhibition of oxygen consumption was independent of the metabolic activity of the tissues.
1.1. The effects of 2,4-dinitrophenol (DNP) and six other phenols on the resting membrane potential and resistance of the crayfish medial giant axon were studied.2.2. DNP (5 × 10−5−10−3 M) caused a concentration-dependent depolarization up to 6 mV which at higher concentrations (1−5 × 10−2 M) turned into a weak hyperpolarization.3.3. Taking into account the changes in membrane potential, the depolarization was accompanied by only slight changes in membrane resistance. The hyperpolarization occured together with a marked decrease in resistance suggesting an increase in resting potassium permeability.4.4. Phenol and most of the other derivatives (4-Cl; penta-Cl and 4-Cl-3, 5-di-CH3) had qualitatively similar effects except for 2,4,6-trinitrophenol (TNP) which showed no depolarizing action.5.5. Neither of the membrane-potential effects is likely to be due to uncoupling of oxidative phosphorylation in mitochondria, since (a) the depolarizing action o DNP had a similar latency (about 5 sec) to that brought about by increasing the extracellular potassium concentration; and (b) TNP, which is known not to act as an uncoupler in intact mitochondria produced a prompt increase in the potassium permeability at a concentration in agreement with the relation between the potency and the octanol-water partition coefficient of the derivatives tested.
The unidirectional influx of neutral amino acids into the brush border epithelium of chicken small intestine has been studied.Tissues depleted of Na+ transported leucine, proline and glycine from a medium devoid of Na+ with a reduced maximal flux (Jm), while no effect was observed on Jm for β-alanine. This treatment had little or no effect on the apparent Michaelis constant for influx (Kt). Jm was partially restored when influx was measured from a Na+-replete medium following a reduction in tissue Na+.The presence of theophylline in the Na+-free preincubation solution prevented the reduction in Jm to varying degrees depending on the substrate. The presence of both theophylline and medium Na+ restored transport rates to the values found under Na+-replete conditions.Dinitrophenol (DNP) substantially inhibited the influx of all substrates inthe presence of Na+. In the absence of Na+, the inhibition of leucine and proline by DNP was again large, but no effect was seen on β-alanine influx, and the effect on glycine was diminished. The action of theophylline in maintaining proline in flux the absence of Na+ was abolished by DNP.Theophylline increased cyclic AMP levels in Na+-replete intestine. A reduction of tissue Na+ increased nucleotide levels almost 2-fold relative to the Na+-replete case, while treatment with theophylline caused an additional 2-fold elevation. In the absence of Na+, DNP increased cyclic AMP levels by 45% relative to a Na+-depleted control. DNP had no effect on nucleotide levels in the presence of Na+.The results are interpreted in terms of a model which envision roles for cellular Na+, cyclic AMP and oxidative metabolism in the activation of neutral amino acid influx in the chicken intestine.
1. Clophen A50 and 2,4,5,2′,4′,5′-hexachlorobiphenyl enhanced the O-demethylation of p-nitroanisole to p-nitrophenol and the content of cyt P-450 in the rainbow trout liver. Dose dependence in relation to time of the induction by Clophen A50 is described.2. Over a 14-day period a single intraperitoneal injection of Clophen A50, 4-, 2,5,2′,5′-tetra- or 2,4,5,2′,4′,5′-hexachlorobiphenyl did not increase the NADPH-cyt c reductase activity or the microsomal protein and phospholipid contents.3. The qualitative pattern of induction by PCBs and chlorobiphenyls of the mixed function oxidase system of rainbow trout liver are discussed in relation to the mammalian aryl hydrocarbon hydroxylase system.
1. Tricaine methanesulphonate is an effective ip anesthetic in a variety of terrestial poikilotherms. It is not a practical ip anesthetic in mammals or birds because of its extremely rapid metabolism in warm-blooded animals.2. The anesthetic doses were similar in all poikilothermic species (150–250 mg/kg), however, mammals required at least a 6 fold increase in dose to produce a transient loss of the righting reflex.3. The whole body concentrations of tricaine associated with return of the righting reflex were of the same order of magnitude in both warm- and cold-blooded vertebrates.4. In 4 of 6 species tested, 90% or more of the eliminated tricaine was accounted for as MABA or its carboxylic conjugates.
1. Anesthesia of rainbow trout (Salmo gairdneri) with 70 ppm tricaine methanesulfonate (MS-222) for 3–9 min resulted in a linear increase in hematocrit.2. Handling of unanesthetized trout caused a higher and more variable hematocrit reading than did exposure to MS-222 for up to 3 min.3. The range and standard error of hematocrit readings was smallest in trout treated with MS-222 for 1 min.
1. The effects of anaesthesia with tricaine (MS 222) and tagging on the blood composition were studied in 123 splakes in Northern Finland. 2. Anaesthetization with tricaine clearly influenced all blood values, except plasma enzyme activities (ASAT, ALAT and SAP). Blood haemoglobin and packed cell volume increased during anaesthesia, and the peak of PCV was reached within 15 min of anaesthesia. 3. the calculated E-MCHC values decreased during anaesthesia and tagging, suggesting swelling of the erythrocytes. The initial haematological values were regained with 3-4 hr of recovery. 4. Anaesthetization elevated the blood lactate concentration and the peak values were measured for splakes anaesthetised and tagged at 1 hr after recovery. 5. The blood glucose was rather stable until the peak was reached within 1 hr of recovery. The initial blood lactate and glucose were regained within 3 and 48 hr, respectively. 6. Repeated anaesthetization had only a slight effect on blood composition, but blood glucose elevated significantly (P less than 0.001) after 4 anaesthetizations.
1. The haemolymph of the sea mussel Mytilus edulis contains three cholinesterases (E.C. and one acetylcholinesterase (E.C. Using fractional (NH4)2SO4-precipitation, the acetylcholinesterase can be separated from other haemolymph proteins, e.g. agglutinins and the other cholinesterases.3. Using gel filtration and ion-exchange chromatography, the desired enzyme could be obtained in a pure form with a specific activity of approximately 100 i.u.4. Molecular weight, determined by gelfiltration, is about 240,000 with subunits of about 39,000 (determined by SDS-electrophoresis); the IP is 4.9 ± 0.1 and the end group determination reveals glycine as N-terminal amino acid.5. The enzyme is active within a broad range; optimum pH is from 6.8–8.0 and optimum temperature from 28–40°C. Michaelis-Menten constants are given for some substrates, and Ki values for inhibitor interactions with the enzyme.
1. The labelling pattern of the genital tract of bulls and rams injected peritesticularly with a single dose of [3H]ethylene dibromide was followed by autoradiography of histological sections of the testes and epididymides of treated animals castrated 6, 12, 24, 48 and 72 hr after injection.2. The radioactivity in the genital tract of the bulls rose at 12 hr and again at 72 hr after injection, whereas in the rams the peak of radioactivity was found 6 hr and 12 hr after injection in the testes and epididymides, respectively.3. In the bull testes the precursor was localized mainly in the cytoplasm of spermatids, whereas in the rams it was scattered in the seminiferous epithelium.4. These results are discussed in connection with the susceptibility of bull and the immunity of ram spermatozoa to the spermicidal action of the above treatment found in previous studies.
1. Of 87 chemicals tested for their ability to interact with oxidized hepatic cytochrome P-450 from mature male brook trout (Salvelinus fontinalis), 21 formed detectable type I or type II binding spectra. 2. When 8 of these 21 chemicals were tested with cytochrome P-450 of nine other species of freshwater fish, wide species variation in hepatic microsomal cytochrome P-450 was evident, since the spectral size of chemical interactions as related to the carbon monoxide spectrum and the ratio of type II to type I binding were not alike. 3. These spectral data suggest that hepatic microsomal cytochrome P-450 of freshwater fish exists in different forms.
1. The n-octylamine difference spectra in all bird species were analogous to the high-spin form of cytochrome P-450 obtained in mammalian species after induction with 3-methylcholanthrene.2. Differences between species were obtained in the ratios of the 430/455 nm peaks in the Soret region for the ethyl isocyanide difference spectra.3. An atypical type I spectral change with methylaniline as ligand was found in one species and the reverse form of this spectral change was obtained in three other species.4. Significant differences between species were also found in the Ks values for aniline and ethyl isocyanide spectral changes and in catalytic activity with different substrates.
1. The movements of 45Ca in the anterior byssal retractor muscle of Mytilus edulis were measured at rest and during contractures induced by ACh or high [K]0.2. The rate of 45CA uptake as measured by the La method was markedly increased during the first 2 min in high-K solution and then decreased to the resting level after 10 min.3. ACh produced no significant increase of 45Ca uptake.4. The results are consistent with the view that ACh-contractures are mainly due to the release of intracellularly stored Ca, while K-contractures are mainly associated with the inward movement of intracellularly stored Ca, while K-contractures are mainly associated with the inward movement of external Ca.
1.1. An open in vitro trout liver perfusion technique has been developed.2.2. Paranitrophenol and paranitrophenol-glucuronide were demonstrated to be the main metabolites of paranitroanisole metabolism in perfused trout liver.3.3. The rate of paranitroanisole metabolism in perfused liver from Clophen A50-treated trout was markedly higher than in untreated trout liver.
1. We have studied the effects of ethanolic extracts of a marine sponge, Dysidea avara, on the development of the eggs of Sphaerechinus granularis and the three substances responsible for this activity have been isolated.2. One of these is avarol, a sesquiterpenoid hydroquinone, the structure of which is already known. The other two compounds are chemically correlated to avarol.3. As a result of treatment of sea-urchin eggs with these three compounds, cleavage is prevented but nuclear division proceeds relatively normally.
1. Specific (3H)-diazepam receptor binding was not detectable in brains of Myxine glutinosa, Lampetra fluviatilis, Squalus acanthias and Chimaera monstrosa, while readily detectable in Calamoichthys calabaricus, Acipenser ruthenus, Salmo salar and Gadus morhua.2. Opiate receptors, in contrast, were found in all investigated species.3. These results indicate that the evolution of benzodiazepine receptors in the brain occurred only in those ancestral fishes giving rise to higher bony fishes and tetrapods.
1. The occurrence of acetycholinesterase (AChE) was investigated in rainbow trout (Salmo gairdneri) whole blood, plasma, erythrocytes and erythrocyte hemolysate.2. No AChE activity was found in the preparations indicating that the enzyme is absent as opposed to it being inhibited by a factor residing in another blood fraction.3. Measurements of AChE in human whole blood demonstrated significant quantities of enzyme and verified the reliability of the assay technique to detect AChE in blood.4. Preliminary assays of AChE in goldfish whole blood and the brain of rainbow trout showed the presence of the enzyme and demonstrates applicability of the technique in fish.
1. The influence of different levels of dietary selenium on the metabolism of selenium in rainbow trout was studied using 75Se as an indicator. 2. Gastric absorption of selenium by the trout appeared to be very efficient. 3. Highest tissue concentrations of selenium were noted in the liver and kidney. 4. Blood did not concentrate selenium and the plasma was the major transport medium. 5. The liver and kidney appeared to be involved in selenium excretion based on high tissue concentrations and variations in half-lives with selenium loading. 6. The biological half-life of selenium in the tissues decreased with increased selenium loading except in the liver, which at toxic dietary selenium concentrations became longer, suggesting a rate-limiting metabolic transformation of selenium for excretion in this organ.
1. Specific inhibition of intestinal alkaline phosphatase by L-phenylalanine was shown in eels adapted to both seawater and freshwater.2. L-phenylalanine-sensitive alkaline phosphatase was demonstrated histochemically at the luminal surface of the sea water eel intestine.3. Net absorption of water, Na+ and Cl− by the everted intestine was reduced significantly by adding L-phenylalanine to both internal and external Ringer incubation medium.4. No appreciable change in transepithelial potential difference was observed by adding 30 mM L-phenylalanine to NaCl, sulfate or choline Ringer solutions.
1. The two naturally occurring catecholamines can produce opposing haemodynamic responses.2. Adrenaline induces increases in central venous pressure and caudal vein pressure; noradrenaline decreases central venous pressure and caudal vein pressure.3. Stroke flow increases with adrenaline administration and decreases with noradrenaline administration.4. Cutaneous vessels are engorged with blood when noradrenaline is given; no change is apparent with adrenaline.5. The implications of these differential responses in relation to the control of circulation are discussed.
1. The activity of dopamine-beta-hydroxylase (DBH) was examined in tissues from Squalus acanthias and Etmopterus spinax using tyramine as substrate. 2. The activity of DBH in axillary bodies in Squalus was 19040 +/- 240 nmol/g per hr and in Etmopterus 6120 +/- 245 nmol/g per hr. 3. DBH activity in nervous tissue, i.e. the splanchnic nerve (together with coeliac artery) was found to be 123 +/- 41 nmol/g per hr in Squalus and 384 +/- 62 nmol/g per hr in Etmopterus. 4. In Squalus heart DBH activity was undetectable, while Etmopterus heart had DBH activity both in atrium and ventricle, 40 +/- 13 and 18 +/- 8 nmol/g per hr respectively. 5. A small amount of DBH activity was found in Squalus blood plasma, 2 +/- 0.7 nmol/ml per hr. 6. The DBH activity gave high formation of octopamine in a wide temperature range from 24.5 to 32 degrees C.
1. Pigeons of either sex were acclimated either to 30°C or to 2°C for 3–4 weeks.2. It was shown that in a cold environment (+6°C) intramuscularly injected noradrenaline (NA) produced hypothermia, which was significantly more effective in the warm-acclimated than in the cold-acclimated pigeon.3. In contrast to the above results at the ambient temperature of +32°C NA produced hyperthermia, and it was found that the cold-acclimated pigeon was more sensitive to NA than the warm-acclimated pigeon at this ambient temperature.4. The reason for this discrepancy in the results is discussed.
1. Norepinephrine (NE) and serotonin (5-HT) were simultaneously assessed in 4 discrete regions of the brain of the golden hamster. 2. Hypothalamic concentrations of both these amines are reported for the following groups: (1) normothermic controls; (2) heat acclimated; (3) cold acclimated; (4) helium-cold hypothermic; (5) rewarming; and (6) rewarmed. 3. Heat acclimated animals demonstrated approximately 35 and 25% decreases from control values for NE and 5-HT, respectively. Cold acclimated hamsters were not significantly different from controls. Helium-cold hypothermia resulted in approximately a 30 and 20% decrease in NE and 5-HT, respectively, with the latter returning to control values during rewarming. 4. The data provide indirect evidence for the involvement of NE in central pathways involving heat gain and 5-HT in pathways involving heat loss, and are discussed in terms of FELBERG & MYER'S (1964 J. Physiol., Lond. 173. 226-236) bioamine theory of thermoregulation.
1. The combined stimuli of short day (9L:15D) and cold exposure (8 ± 2°C) produced a positive response to norepinephrine resulting in nonshivering thermogenesis (metabolic rate 23% above basal metabolic rate), stimulated growth of brown adipose tissue and effectively raised the mean lowest daily rectal temperatures of the white rat over warm-acclimated conditions (21 ± 2°).2. Exogenous melatonin was effective in depressing the mean daily lowest rectal temperature under warm acclimated conditions and raising the mean daily lowest rectal temperatures of long day rats under cold conditions. It apparently overrode the effect of a long day.3. The combination of cold acclimation and short day potentiated by melatonin induced an increase (P > 0.02) in mean pineal weight over long day, melatonin-treated, cold-acclimated rats.4. Although the short day, warm experiment did not produce “cold acclimation without cold” as shown in other laboratories, the short day, cold experiment did produce indices of cold acclimation not seen in the long day, cold experiment. This would be predicted from adaptation observed in mammals in the free environment.
Euglena gracilis was cultured with different concentrations of an essential metal and a non essential one: Cu and Cd. Cu even at high concentrations did not affect the growth rate, while Cd reduced it according to the concentration used. Cu concentration stayed always lower in the cells than in the medium, instead Cd was accumulated in the cells.From cells and medium of cultures treated with copper a glycopeptide which chelated copper and zinc was isolated. It was present in the control culture too, but it linked only Zn; its molecular weight is lower than 10,000 D.From cells cultured with Cd a compound of a very high molecular weight (higher than 100,000 D) was isolated: it linked Cd and Zn.The concentration of Zn in the medium and in the cells linked to the compounds is also discussed, and a model is proposed for regulation of physiological metals in organisms; it may explain how detoxification relates to regulation of heavy metals.
1. Coho salmon, exposed to sublethal levels of aqueous copper (1/4 and 1/2 LC50), lost appetite and ceased growing or showed decreased rates of growth. 2. Recovery of appetite and growth rate was faster in fish exposed to 1/4 of the LC50 than in those exposed to 1/2 of the LC50. 3. Copper levels were elevated in liver gill and kidney of exposed fish with the liver tissue accumulating a much larger amount of the metal than any other tissue. 4. The concentration of liver copper became constant at about the time that growth rate recovered. 5. The exposed fish exhibited much higher resistance to elevated aqueous copper levels than did the controls. 6. The results suggest that coho salmon may become acclimated to higher levels of copper and that acclimated fish are more tolerant to copper than control animals.
1. Rainbow and brown trout were exposed to sub-lethal concentrations of cadmium in aquaria for either 2 weeks or 3 months.2. Cadmium accumulation in the gills, liver and kidney of exposed fish was significantly greater than in control fish.3. The activity of several enzymes measured in liver, gills, plasma and red blood cells was unaffected by exposure of the fish to cadmium.
1. Tryptamine is acetylated in retinal homogenates to N-acetyltryptamine by the enzyme N-acetyl (NAT).2. TLC using two different solvent systems confirmed that the product of the enzyme reaction was indeed N-acetyltryptamine).3. The rate of acetylation by NAT varied over a twenty-four hour period with maximal activity occurring at 12 midnight.4. Cycloheximide and exposure to light attenuated the night-time rise in NAT while drugs known to a affect the noradrenergic, serotoninergic, and GABAergic neurotransmission had no effect.
1.1. Various tissues of adult Locusta migratoria, Astacus leptodactylus, Mytilus edulis and Helix pomatia were analyzed for monoamine oxidase (MAO) and N-acetyltransferase activity directed against octopamine.2.2. MAO activity against octopamine was detectable in Mytilus muscle and Locusta Malpighian tubules. No activity was found in any other tissue of the species studied (Astacus not investigated).3.3. Low MAO activity against 5-hydroxytryptamine (5-HT) and dopamine (DA) was present in Helix tissues (about 1% of that found in rabbit tissues).4.4. N-Acetylation of octopamine, 5-HT and DA was prominent in Locusta nerve tissue and Malpighian tubules, and high in other locust tissues and in Astacus nerve tissue. Relatively low activity was found in skeletal muscle of these species.5.5. N-Acetylation of octopamine was enhanced by the addition of acetyl CoA. With 14C-labelled acetyl CoA, the label appeared in the acetylated product, which was identified as N-acetyl-octopamine.6.6. Addition of acetylcholine and eserine enhanced N-acetylation of octopamine in locust nerve tissue (by inhibiting cholin-acetylase which competes for acetyl CoA), but not in other locust tissues and in crayfish tissues.7.7. No N-acetylase activity was found in Helix and Mytilus.8.8. It is concluded that N-acetylation is the predominant mechanism of octopamine metabolism in arthropod tissues, particularly in the nervous system.
1. The ionophoretic application of acetylcholine (ACh) onto somata in the suboesophageal ganglionic ring of the mollusc Heobania, produced biphasic or monophasic membrane potential changes.2. The ACh hyperpolarizing potentials usually had the equilibrium value of −58 ± 5 mV and were associated with a Cl−-conductance change. However in some nerve cells the reversal level ranged from −45 mV to −51 mV and varied with changes in the (Cl−)0 ang in (Na+)0. The depolarizing potential changes to ACh application were associated with Na+-conductance increase.3. The possibility that the monophasic and biphasic responses arose from the activation of distinct types of ACh receptors was further investigated by comparison of responses to cholinomimetics and by application of cholinolytics.4. It was concluded that many populations of cholinergic receptors exist, which are pharmacologically distinct.
1. The response to various acetylcholinesterase (E.C. and cholinesterase (E.C. inhibitors on the hydrolysis of acetyl-1 14C-choline iodide by extracts of adult Schistosoma haematobium, S. mansoni, S. mattheei and S. bovis was studied.2. Eserine (physostigmine) produced total inhibition at concns between 6 × 10−4 M and 1 × 10−15 M.3. The cholinesterase inhibitors, Lysivane, Tiguvon and iso-OMPA produced a slight inhibition.4. The enzymes were partially inhibited by the mammalian acetylcholinesterase inhibitors 62C47 and 284C51.5. Female S. haematobium enzyme was more sensitive and male S. haematobium enzyme more refractory to metrifonate (Bilarcil) than other species.
Choline acetylase and acetylcholinesterase activities were measured in single Drosophila embryos and in cell cultures prepared from single embryos. Acetylcholinesterase activities appeared first in vivo and in vitro, followed, about 4 hr later, by choline acetylase activities. The orders of appearance and the rates of increase of these enzyme activities were similar in vivo and in vitro, indicating that a program for enzyme elaboration was operating within the cells. In vitro the appearance of acetylcholinesterase activities was correlated with the completion of axon formation.
1.1. The relation of Ach-sensitivity of the nerve cell membrane to the activity of the Na pump was studied.2.2. The depolarizing effect of Ach is greater when the Na pump is in an inactive state.3.3. Activation of Na pump work leads to the decrease and inactivation to the increase of the Ach-effect on the membrane conductivity.
1. The regional distribution of cholinacetyltransferase (CAT) was determined in the main subdivisions of the brain of 20 vertebrates from cyclostomes to mammals.2. The lowest whole brain values were found in cyclostomes, primitive bony fish and Amphibia. The highest activities were observed in the electric ray (Torpedo) and teleosts.3. Within vertebrate classes the CAT pattern was relatively uniform.4. An increasing CAT activity was observed in the telencephalon from lower to higher forms.5. The relatively high production of acetylcholine in the brainstem of all vertebrates studied may be regarded as an phylogenetically old characteristic whereas pronounced cholinergic activity in the telencephalon marks a phylogenetically late development.
1. The interaction of two specific ligands for the vertebrate nicotinic acetylcholine receptor were investigated on the solubilized form of a proposed acetylcholine receptor from the invertebrate Limulus polyphemus. 2. The affinity agent 4-(N-maleimodo)benzyltrimethylammonium iodide exhibited no effect on the binding of alpha-bungarotoxin to the Limulus receptor protein. 3. Torpedo acetylcholine receptor antibody neither inhibited alpha-bungarotoxin binding nor produced any alteration in the sedimentation profile of the Limulus receptor. 4. The lack of interaction of 4-(N-maleimido)benzyltrimethylammonium iodide and Torpedo acetylcholine receptor antibody with the Limulus acetylcholine receptor was interpreted to reflect significant difference between the molecular structures of this invertebrate receptor and the acetylcholine receptor of vertebrate.
1. Acetylcholine and its biosynthetic and degradative enzymes (choline acetyltransferase and acetylcholinesterase, respectively) were quantified in several defined structures from the central nervous system of the tobacco hornworm Manduca sexta at various times during postembryonic development.2. Activity of choline acetyltransferase, the key enzyme of the cholinergic pathway, changes roughly synchronously and similarly in the protocerebrum and subesophageal, prothoracic, and third abdominal ganglia, and it increases dramatically in developing antennal and optic lobes.3. Levels of acetylcholine and of specific acetylcholinesterase, which is the principal cholinesterase in the nervous system, also rise greatly during metamorphosis of the central nervous regions.4. The major changes in the activity of choline acetyltransferase correlate with known developmental endocrine events.
Top-cited authors
Robert James Walker
  • University of Southampton
Ronald Nachman
  • United States Department of Agriculture
Laura Canesi
  • Università degli Studi di Genova
Michael Norman Moore
  • University of Exeter
Philip S Rainbow
  • Natural History Museum, London