Colon Activation by Intravenous Hypertonic NaCl Injection in Unanesthetized,Trained Dogs

Abstract

Since Hughson and Scarff 1 first reported peristaltic augmentation of the ileum after NaCl intravenously in anesthetized cats, several investigators have confirmed the observation. 2 , 3 , 4 , 5 Regarding the response of the colon no action has been experimentally demonstrated. Thus our results seem interesting since they show that the large intestine can be activated by salt solutions of adequate hypertonicity when intravenously administered.

This work was carried out in unanesthetized, trained collies, which had undergone cecostomy after the method described by Plant and Miller. 6 Rubber balloons of convenient size, under uniform water pressure were inserted into the anterior colon and registrations were recorded through a closed system 6 by means of Mendenhall's 7 modified Brodie 8 bellows. Varying amounts, 2 to 15 cc., of NaCl 5% and 20% concentration were injected intravenously and intracardially.

Results. 5% NaCl only slightly (a) augments colonic tonus, (b) increases peristaltic amplitude.

5% NaCl does not alter peristaltic frequency.

5% NaCl shows little or no disturbance of frequency and amplitude of rhythmic waves.

20% NaCl definitely (a) augments colonic tonus, (b) increases peristaltic amplitude, (c) induces peristalsis, in the quiescent, atropinized colon.

20% NaCl shows little or no augmentation of frequency and amplitude of rhythmic waves.

Similar amounts of normal saline fail to affect the colon.

20% NaCl, 1.0 cc. per kg., as here administered did not produce vomiting or retching movements.

5% and 20% NaCl failed to produce defecation in these particular experiments.

No evident distress was ever observed in over 20 experiments.

Conclusions. Reasonably small amounts of hypertonic NaCl solutions intravenously injected promote or augment activity of the colon. Since this increased activity can be induced after atropinization, NaCl, in this instance, probably affects either Auerbach's plexus or the intestinal muscularis directly.