Excitatory action of pilocarpine on secretion of the stomach. Action of enterogastrone on gastric secretion induced by that substance

Abstract

We have thought it interesting study pilocarpine’s ac­ tion over the gastric secretion when injected intravenously in a continued form and also of a single injection of pilocarpine over the constant gastric secretion induced by histamine.

On these experiments 18 cats were used on which we perfo- med a «total bag stomach». They were anaesthetized with dial, chloralose or somnilefa (spanish somnifen). Pilocarpine was injected intravenously in varied dosage continously. With 6 y/kg/min. a gastric secretion is produced which stabilizes 2 hrs after the injection. As the dosage is raised the volunte of gastric juice segregated is raised up to 26 y/kg/min. Higher doses do not produce a rise in the volunte segregated.

The free and total acidity raise progressively but do not reach as high a valué as when histamine is used as stimulant. The valué of total chlorine is analogous to the histaminic juice (table 1). Mucus only appeared when the continuous in­ jection was maintained during a prolonged time.

Over the constant secretion induced by. histamine the single injection of pilocarpine (table 2) produces a sharp rise in the amount of juice segregated, the original level is again re- covered after 40-60 minutes. Higher rises are observed when injected doses of pilocarpine are inferior to 0.1 mg/kg that when higher dosage are used. Acidity augmentes little and not always, total chlorine is lowered in almost all experiments.

Pilocarpine thus, is capable of stimulating the parietal cells not only at rest but also when these are stimulated by hista­ mine. It seems thus, that the mode action of pilocarpine and histamine over the parietal cells of the stomach is not the same. In order to clarify where the difference of action lies we have studied the action of enterogastrone over the secretion induced by pilocarpine.

We have administered enterogastrone to cats on which \ve liad obtained constant gastric secretion by nieans of pilo­ carpine, not finding any inhibitory effect.

The injection ofi enterogastrone to cats with constant gastric secretion induced bjr histamine produces a marked lowering of said secretion. Ulterior injection of pilocarpine during the inhibitory period provoked by enterogastrone produces a rise in the secretion in most cases as if enterogastrone vvas never injected (table 3).

Pilocarpine’s action over the gastric secretion is exerted peripherically over the mucous cells, stimulating the parietal cells but also acts adding its stimulating action to that of histamine.

Most probably it acts over the parietal cells at a different point that histamine, this idea is supported by the fact thatenterogastrone inhibits the action of pilocarpine in some cases only, while it always paralizes the action of histamine.