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ABSTRACT: The effect of intravenous histamine on intragallbladder pressure (GBp) and subsequent modification of the histamine response by H1- and H2-antagonists was investigated in an awake baboon model. Responses to specific H1- and H2-agonists were also examined in order to further elucidate gallbladder histamine responses. Gallbladder volume (GBv) was arbitrarily set at 60-70% of observed resting GBv, and drugs were then infused intravenously with continuous monitoring of GBp. Histamine administration resulted in a logarithmic dose--response curve with a maximal increase in GBp equal to 31.7 mm Hg at a dose of 0.0625 mg of histamine. Infusion of the H1-antagonist diphenhydramine hydrochloride (Benadryl) resulted in a decreased GBp response to histamine when compared to preblocker response at all doses studied. On the other hand, histamine response following administration of the H2-antagonist metiamide was significantly greater than the preblocker histamine response. Infusion of the H1-agonist 2-pyridylethlamine resulted in a dose-dependent increase in GBp similar to the histamine curve, while infusion of the H2-agonist dimaprit resulted in consistent decreases in GBp. These results extend previous observations in subprimate preparations and demonstrate the presence of both stimulatory H1-receptors and inhibitory H2-receptors in an in situ primate model.
Digestive Diseases and Sciences 05/1983; 28(4):353-8. · 2.12 Impact Factor
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Journal of Surgical Research 09/1982; 33(2):146-50. · 2.25 Impact Factor
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ABSTRACT: Biomechanical theory was applied to devise a dynamic method for describing gallbladder tone in an in situ baboon model. Under pentobarbital sodium (Nembutal) anesthesia, cyclical infusion of bile into and withdrawal of bile from the gallbladder with continuous pressure monitoring allow instantaneous measurement of the pressure-volume ratio and thus of mean gallbladder compliance. This paper describes the method and details the manner of data analysis. Pharmacologic and hormonal agents with known gallbladder effects are used in order to demonstrate the sensitivity of the method. Pilocarpine, histamine, and cholecystokinin cause contraction of the primate gallbladder smooth muscle; this contraction is reflected in decreased compliance by continuous monitoring. Atropine administration results in increased ability to accommodate volume infusions; this effect has not been demonstrated by static monitoring in previous experiments. This new method allows continuous monitoring of compliance and offers both simplicity and sensitivity when compared with previous methods.
The American journal of physiology 12/1981; 241(5):G376-81.
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ABSTRACT: Utilizing histamine and selective agonists for H1- and H2-receptors, we examined the pH dependence of histamine-stimulated tension changes in guinea-pig gallbladder, which contains both contracting H1-receptors and relaxing H2-receptors. In muscle strips contracted with histamine and pH 7.3, increasing pH to 7.8 raised tension further (P less than .025), while decreasing pH caused a fall in tension (P less than .025). The H2-agonist Dimaprit relaxed tension at pH 7.3 and increasing the pH decreased the relaxation (p less than .0125). Contractions in response to H1-agonist 2-pyridylethylamine at pH 7.3 were unchanged when pH was elevated but decreased when pH was lowered (P less than .05). Tension changes in response to slow pH alterations suggested that H1-receptor activity is inhibited below pH 7.1 and H2-receptor activity is inhibited above pH 7.6. These reversible changes in activity probably reflect changes at H1- and H2-receptors rather than alterations in the ionic species of histamine.
Journal of Pharmacology and Experimental Therapeutics 07/1981; 217(3):638-44. · 3.83 Impact Factor
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Journal of Surgical Research 05/1980; 28(4):373-8. · 2.25 Impact Factor
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Current Surgery 37(3):204-8.
