Potentiation of secretin stimulation of the pancreas

Abstract

1. In fasted anaesthetized cats which were secreting pancreatic juice at a steady slow rate in response to continuous intravenous infusion of secretin, stimulation of the dorsal vagus trunk increased the rate of secretion, the rate of output of amylase and the concentration of bicarbonate in the juice.2. The increase in rate of secretion and in concentration of bicarbonate was reduced but not abolished by atropine. It was unaffected by adrenergic blocking agents, but abolished by hexamethonium.3. No increase in rate of secretion of secretin-stimulated juice was observed on cervical stimulation of vagus nerves in which the efferent fibres had degenerated after supra-nodose section of the nerves. It is concluded that the increase in secretion rate is mediated by ;atropine-resistant' efferent vagal fibres.4. Pancreozymin, antral extracts and histamine increased the rate of secretion of secretin-stimulated juice. Pancreozymin and antral extracts also increased the rate of amylase output. These effects of pancreozymin and antral extracts were not abolished by atropine or hexamethonium.5. As vagal stimulation pancreozymin, antral extracts and histamine have little or no effect on the resting pancreas of the anaesthetized cat, it is concluded that they exert a potentiating effect on secretin. It is suggested that the mechanism of this potentiation is an increase in pancreatic blood flow, which facilitates the supply of secretin to the gland.

Secretin and insulin: Response to intraduodenal acid

“…This would suggest IRI 20 that cholinergic mechanisms facilitate the response of ;u/mt 10 the 'S' cells to hydrochloric acid. This concurs with the 0 findings of earlier workers using secretion of pancrea-50 tic fluid and bicarbonate as evidence of secretin release [13,14,15]. There are three types of mechanism ~0 possible: (i) the vagus nerve; (ii) local cholinergic ms 30 pglmI reflexes independent of the vagus and (iii) both (i) and 2o (ii) together.…”

The action of secretin, cholecystokinin‐‐pancreozymin and caerulein on pancreatic secretion in the rat

“…In other species, for example dog, CCK-PZ stimulates only a moderate secretion of fluid compared with that simulated by secretin (Preshaw, Adashek, Cooke & Grossman, 1965) while in the cat CCK-PZ stimulates no secretion of juice at all, although secretin is a strong stimulant ofthe rate offlow (Brown et al 1967;Way & Grossman, 1970). However, comparisons, such as these, between species can be more directly made by expressing rate of flow in terms of flow per unit weight of gland.…”

The Effect of Cycloheximide on Cholecystokinin‐evoked Pancreatic Juice of the Anaesthetized Rat

“…In the cat. where administration of cholecystokinin alone does not cause formation of any juice at all (Brown et al., 1967), it would appear tliat cholecystokinin does not cause production of any appreciable volume of carrier fluid, but in the dog (Debas and Grossman, 1973) and, more particularly, in the rat (Sewell and Yonng, 1975), it is obvious that the hormone can ijrovoke secretion of Quid as well as of enzymes.…”