Search

The subtypes of purinoceptors in the pancreatic duel have been investigated by applying ATP, UTP and benzoylbenzoyl-ATP (BzATP) to basolateral and luminal surfaces of pancreatic ducts isolated from the guinea-pig pancreas. Changes in intracellular Ca^2+ concentration ([Ca^2+]i) were measured by microfluorometry in microperfused interlobular duct segments. Both ATP and UTP caused biphasic concentration-dependent increases in [Ca^2+]i, in pancreatic duct cells when applied to either the basolatcral or luminal membrane. Cross desensitization between ATP and UTP did not occur. BzATP increased [Ca^2+]i when applied to the luminal membrane. These data suggest that multiple P2Y receptors are localized to both the basolateral or luminal membranes, while P2X receptor is localized to the luminal membrane.

The effect of two-hour running on the postprandial gastric secretion was studied in four conscious dogs with a Heidenhain pouch. Gastric acid secretion from the Heidenhain pouch was not altered during the first hour of the exercise. During the second hour, however, acid secretion was significantly depressed when the speed of the treadmill was 4 km/h or 6 km/h, compared to the non-exercise control. A discrepancy existed between the older and the recent literatures, in that gastric secretion was depressed by the exercise in the older studies and it was unaffected in the recent studies. From our experiments, this discrepancy could be due in part to the experimental design since gastric juice was collected over two hours in the older studies and less than one hour in the recent studies. Pepsin secretion from the Heidenhain pouch was decreased after a meal whether the animals had exercise or not. During the second hour of running at a speed of 4 km/h, pepsin output was slightly but significantly higher than the nonexercise control. The bowel movement occured soon after the exercise. This effect on the defecation might be useful for the patients with constipation and further studies should be done.

The effect of 2-hour running on gastric emptying and gastro-intestinal motility was studied in four conscious dogs with gastric and duodenal fistulae. Gastric emptying of a liquid meal (Sustagen) was not altered during the exercise. Gastrointestinal tract has been shown to contract every 100 minutes. This interdigestive contraction was not observed during the exercise. Instead, irregular small contraction was present. After cessation of the exercise, interdigestive contraction appeared at the expected time intervals, 200 minutes after the pre-exercise interdigestive contraction. In conclusion, exercise did not affect the gastric emptying of liquid meals, but depressed interdigestive contraction of the stomach and upper small intestine.