THE DIFFERENCE IN ACTION OF PARASYMPATHETIC DRUGS IN APPLICATION TO SEROSA OR MUCOSA OF THE ISOLATED INTESTINE

Abstract

Trendelenburg''s method of registering peristaltic and pendular movements of the isolated rabbit''s and guinea pig''s intestine has been modified, so that substances could be brought in contact with either the serosa or mucosa. The spastic effect of choline ester (choline, acetyl-choline, carbamylcholine, acetyl-[beta]-methyl choline) and his-tamine on the tonus of the longitudinal muscles and the complete relaxation produced by atropine when added to the bath fluid, are not obtained when these substances are brought into the intestinal lumen, although at higher concns. The choline esters applied to the serosa tend to stimulate the pendulum and peristaltic movements, but the spastic tonus increase may interfere with both, preferentially the pendular movements. Choline esters applied to the mucosa tend to stimulate peristalsis first, secondarily the pendular waves; atropine passing through the mucosa causes a decrease of the peristaltic and less of the pendular movements. If atropine is applied to the serosa, after either atropine or choline esters have been introduced into the intestinal lumen, the tonus is abolished but longitudinal waves alone or peristalsis also persist. The action of histamine is equally altered by application to the serosa; but this substance is quite variable in any application. The response of the intestine to autonomic agents depends largely on the initial tonus and motility of the strip used. The possible mechanism of some of the observed reactions of the intestine is discussed. The observations suggest that autonomic drugs, if efficacious orally, act not locally on the intestine but are first absorbed into the circulation and then return with the blood stream.