How does morphine work on colonic motility? An electromyographic study in the human left and sigmoid colon.
ABSTRACT The effect of morphine on colonic motility was investigated by recording the colonic myoelectric spiking activity by means of a 50 cm long silastic tube equipped with 4 bipolar AgAgCl ring electrodes fixed at 10 cm intervals that was introduced into the left colon in 8 healthy subjects by flexible sigmoidoscopy. Tracings were obtained for 1 hour in the fasting state and for another 1 hour after i.m. injection of morphine sulphate 0.15 mg/kg. The different types of spike bursts were compared before and after morphine injection. The control tracings showed that the spiking activity of the colon was made of 2 types: 1)- Rhythmic Stationary Spike Bursts (RSB), that were seen at only one electrode site; 2)- Sporadic Bursts, that were either propagating over all 4 electrodes (SPB) or non propagating (SNPB). Injection of morphine was followed by 1)- a considerable increase in the number of RSB from 107 +/- 43 bursts/hour (mean +/- SEM) to 491 +/- 23 bursts/hour; 2)- the complete disappearance of the SPB dropping from 7.3 +/- 2.0 bursts/hour to 0.3 +/- 0.2 bursts/hour; 3)- no significant change in SNPB (from 52 +/- 4 bursts/hour to 57 +/- 5 bursts/hour). These results indicate that 1)- stimulation of colonic smooth muscle activity by morphine seems to result from an increase in the number of rhythmic stationary bursts; 2)- however inhibition of colonic transit may be related to the decrease in the number of sporadic propagating bursts.
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ABSTRACT: . Postoperative intestinal atonia is a complication which is likely to occur in patients predisposed for constipation and in patients after intra-abdominal operations. The postoperative delay of bowel movement, however, is often also related to the type of anaesthesia being used. In order to evaluate the magnitude of an anaesthetic-induced postoperative delay of bowel movement, two types of intravenous-based anaesthesia using fentanyl/midazolam (1 mg/25 mg; dosage 0.1 ml/kg/h), and ketamine/midazolam (250 mg/25 mg; dosage 0.1 ml/kg/h) respectively were compared with a volatile anaesthetic technique (enflurane; mean concentration 1.5 vol%). Methods. In three groups of patients (each n=15) undergoing elective surgery of the lower extremities, induction of anaesthesia was accomplished with methohexital (1 – 1.5 mg) followed by succinylcholine (1.5 mg/kg) to facilitate intubation. For the maintenance of muscle relaxation vecuronium bromide was used. All patients were given droperidol to prevent postoperative emesis, and they were artifically ventilated with N2O/O2 (60: 40) to normal end-expiratory CO2 concentrations. No anticholinergic agents were used at the end of operation since they are known to interfere with bowel motility. In order to determine gastro-intestinal motility, the H2 exhalation test was used. For this purpose 40 g lactulose in 100 ml of water was given to all patients via a gastral tube shortly before extubation. Lactulose is broken down by bacteria once it enters the colon, and H2 is released, taken up by the vascular system and exhaled. Postoperatively, patients were asked to exhale into a 20-ml syringe every 10 min. The content was analysed for hydrogen (ppm), using an electrochemical sensor (GMI exhaled hydrogen monitor). From the time of lactulose instillation to a threefold increase in endexpiratory hydrogen concentration (compared to the preoperative value), gastro-coecal transit time was computed. Results. All three groups of patients were comparable in age, height and body weight. Also, the duration of operation was comparable in all three groups. Mean gastro-coecal transit time was 204 (19.6 SD) min following enflurane, 302 (32.8 SD) min following fentanyl/-midazolam and 210 (28.8 SD) min following ketamine/midazolam anaesthesia. The gastro-intestinal inhibition after the opioid-based anaesthetic technique was significantly prolonged (pDer Anaesthesist 01/1994; 43(2):87-91. · 0.74 Impact Factor
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ABSTRACT: More than half of those who use opiates suffer from constipation, and withdrawal from opiates produces abdominal cramps and diarrhea in 70% to 85%. These withdrawal symptoms may influence the number of opioid-dependent patients who attempt abstinence and the number who relapse. To characterize the motility correlates of these gastrointestinal symptoms of withdrawal, six patients from a drug treatment program were studied while on maintenance doses of methadone (average of 57.5 mg/d) and during acute naloxone-precipitated withdrawal. Motility was recorded via open-tipped catheters at 30 cm and 15 cm from the anal verge during a 15-minute baseline period and for 15 minutes during mechanical distention of the rectosigmoid colon with a balloon. This sequence was repeated during withdrawal. Subjective symptoms and objective signs of withdrawal assessed at 15-minute intervals showed that all six patients experienced withdrawal. Sigmoid and rectal motility were also assessed in 18 opiate-free control subjects. Long-term methadone use was associated with normal sigmoid and rectal motility under baseline conditions, but methadone users did not show the inhibition in sigmoid motility that normal subjects exhibited following baloon distention. When withdrawal was precipitated by naloxone, methadone users showed significant increases in rectosigmoid motility in association with signs and symptoms of withdrawal.Neurogastroenterology and Motility 06/2008; 2(2):90 - 95. · 2.94 Impact Factor
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ABSTRACT: The effects of different opioid agonists on spontaneous mechanical activity and response to electrical transmural nerve stimulation of both longitudinal and circular muscle strips from the human colon were studied by using a superfusion apparatus to record isometric contractions. Exogenously added opioid agonists did not modify the spontaneous contractile activities of both types of strips. Nerve stimulation induced a triphasic response composed of a first contraction C1 followed by a relaxation C2 and an off-contraction C3; this response was mediated by cholinergic excitatory nerves and non-adrenergic, non-cholinergic (NANC) excitatory and inhibitory nerves. The delta-agonists methionine enkephalin, [D-Pen2, D-Pen5] enkephalin (DPDPE) and the kappa-agonists dynorphin, trans-3,4 dichloro-N-methyl-N-(2-[1 pyrolidinyl]-cyclohexyl) (U-50488H) decreased the amplitudes of the contractions C1 and C3 of both strips in a dose-dependent manner. The selective mu-agonist D-alaglymepheglyol (DAGO) decreased the contraction C1 of longitudinal and circular muscle at high dose (1 μM) and often reduced the relaxation C2 of both types of strips at low dose (0.05 μM), finally, naloxone, but only at higher concentrations (1 μM) decreased the C1 amplitude significantly in circular muscle. In conclusion, these data suggest that mu, delta and kappa opioid receptors are involved in the neuro-regulation of smooth muscle of human colon and that opioid agonists modulate both excitatory and inhibitory neurotransmission through an action on cholinergic and non-adrenergic, non-cholinergic neurons.Neurogastroenterology and Motility 06/2008; 5(4):289 - 297. · 2.94 Impact Factor