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P Thor

Publications and source records attributed to P Thor.

At least 55 records · Page 3Linked to original sources
PubMed1976

Comparison of vasoactive intestinal peptide (VIP) and secretin in gastric secretion and mucosal blood flow.

VIP and secretin were compared in regard to their effects on gastric acid and pepsin secretion induced by pentagastrin histamine or a peptone meal as well as on gastric mucosal blood flow and meal induced serum gastrin level in conscious dogs provided with gastric fistulas and denervated fundic pouches. Both VIP and secretin caused a dose-related stimulation of basal pepsin outputs and inhibition of pentagastrin-induced acid secretion. VIP, like secretin, inhibited pentagastrin and meal-induced gastric acid secretion but in contrast to secretin it caused inhibition of acid response to histamine. Inhibition of acid secretion by VIP or secretin was accompanied by secondary reduction in gastric mucosal blood flow in tests with pentagastrin or histamine and by depression of the serum gastrin level in tests with a peptone meal. This study indicates that in comparison with secretin, VIP has a wider spectrum of inhibition of stimulated gastric secretion and may be considered as one of the enterogastrones released in the small intestine.

Aminopyrine↗
PubMed1975

Cyclic-AMP and pancreatic bicarbonate secretion in response to secretin in dogs.

In anesthetized dogs given secretin intravenously in doses doubling every 60 min and ranging from 0.5 to 8 units per kg body weight per hr, cyclic-AMP levels in pancreatic tissue rose continuously, whereas DNA concentrations were slightly decreased. Bicarbonate concentrations and bicarbonate outputs, cyclic-AMP tissue concentrations and bicarbonate outputs, as well as cyclic-AMP tissue concentrations and juice outputs, were significantly correlated. In conscious pancreatic fistula dogs, there was also a significant correlation between cyclic-AMP and bicarbonate concentrations and outputs in the pancreatic juice after stimulation by exogenous secretin. Accordingly, enhanced release of endogenous secretin achieved by intraduodenal acidification led to a dose-dependent increase in bicarbonate and cyclic-AMP outputs in both conscious and anesthetized dogs. Phosphodiesterase inhibitors (aminophylline, caffeine, and papaverine) given alone to the conscious dogs did not initiate pancreatic bicarbonate secretion, but they potentiated bicarbonate responses to exogenous secretin. These data suggest that cyclic-AMP plays a part in secretin-stimulated pancreatic secretion.

Aminophylline↗
PubMed1975

Comparison of secretin and vasoactive intestinal peptide on pancreatic secretion in dogs.

Vasoactive inhibitory peptide (VIP) and secretin were compared in regard to the stimulation of pancreatic bicarbonate secretion and the augmentation of pancreatic response to caerulein or a peptone meal in chronic gastric and pancreatic fistula dogs. Dose-response analysis showed that maximal bicarbonate response to VIP was about 17% of that to secretin. Both caerulein and endogenous cholecystokinin, released by a peptone meal, clearly potentiated pancreatic bicarbonate response to VIP in a manner similar to secretin. The interactions of these two peptides showed that VIP is a potent inhibitor of secretin-induced pancreatic secretion. From the dose-response curves to secretin alone and secretin plus VIP, Michaelis-Menten analysis showed typical competitive inhibition, which indicates that VIP and secretin share a common receptor site.

Amylases↗
PubMed1974

The role of vagal innervation in gastric and pancreatic responses to meals varying in pH.

In three dogs provided with chronic gastric and pancreatic fistulae, gastric acid response to a peptone meal was measured by a method of intragastric titration at pre-selected pH values ranging from 6.0 to 2.0 or at a constant pH during intravenous infusion of secretin in graded doses ranging from 0.25 to 4.0 u./kg.hr. Simultaneously, pancreatic secretion was determined by the standard collection technique and serum gastrin response was measured by radio-immunoassay. In this way the pH profile for the inhibition of gastric response and stimulation of pancreatic secretion as well as serum gastrin response to a peptone meal have been determined and compared with that obtained with exogenous secretin or feeding a liver meal. Truncal vagotomy resulted in a significant decrease of gastric acid response to the meal at all pH levels or at all doses of secretin but the inhibitory effect of gastric acidification or secretin on serum gastrin and gastric acid response to a meal remained unchanged. Vagotomy caused a decrease of pancreatic secretory response to meals at all pH levels and at all doses of secretin except the largest one. Pancreatic secretion stimulated by secretin alone was not affected by vagotomy, whereas that induced by feeding a liver meal was markedly decreased by this procedure. From these studies we have tentatively concluded that the vagus nerve facilitates the release of intestinal hormones and that vagotomy causes a decrease of gastric and pancreatic responses to endogenous but not to exogenous stimuli.

Animals↗
PubMed1974

Gastric and pancreatic responses to meals varying in pH.

1. Gastric acid response to a test meal of 10% peptone was measured in chronic gastric and pancreatic fistula cats using the Fordtran and Walsh method, monitoring the rate at which a solution of 0.5 M sodium bicarbonate had to be added to maintain constant pH of gastric content at pre-selected values ranging from 5.0 to 1.0. Simultaneously, pancreatic secretion was determined by the standard collection technique. In this way the pH profile for the inhibition of gastric secretion and stimulation of pancreatic secretion has been established in cats.2. A peptone meal adjusted to pH 5.0 produced gastric acid output similar to the maximal response to histamine or pentagastrin. It provoked a negligible stimulation of pancreatic flow rate and bicarbonate output but a large protein output.3. Graded decrease of the peptone meal pH to below 4.0 resulted in inhibition of gastric acid production and in a concomitant stimulation of pancreatic secretory volume and bicarbonate output. A meal adjusted to pH 1.0 stimulated gastric secretion only about 30% of the response recorded at pH 5.0. Pancreatic secretion with a meal adjusted to pH 3.0 reached the highest level of about 70% of the maximal response to exogenous secretin.4. Since the observed changes in the secretory activity of the stomach and the pancreas induced by test meals adjusted to pH 3.0 can be fully reproduced by exogenous secretin, it is suggested that in the cat this hormone may be responsible for the gastric inhibitory and pancreatic stimulatory mechanisms activated during normal digestion of food.

Animals↗