Changes in intestinal volume with hemorrhage

¹ Department of Physiology, Western Reserve University School of Medicine, Cleveland, Ohio; and Department of Physiology, Indiana University School of Medicine, Indianapolis, Indiana

The purpose of these experiments was to study the changes in intestinal volume occurring with hemorrhage, utilizing a gravimetric technique which permitted a study of small segments of the intestine. It had been observed previously that intestinal weight often increased in the upper small intestine during hemorrhage, while in the lower small intestine it usually decreased. In studying the latter effect it was found that sympathetic nerve activity and reduction of venous pressure were both important in decreasing intestinal volume. Changes in tonus and local reduction in arterial pressure did not appear to be important. The increase in volume with hemorrhage appeared due to epinephrine discharge from the adrenal medulla since it was eliminated by adrenalectomy. Local pressure changes and alteration of tonus were eliminated as causal factors. It appears that systemic hypotension induces sympathetic discharge which in turn may cause either an increase or a decrease in intestinal blood volume. Sympathetic discharge over the vasoconstrictor fibers reduces blood volume while adrenal medullary secretion increases it. The observed response is apparently a resultant of these two antagonistic effects.

Note:
With the Technical Assistance of Stuart L. Graham and Robert Bernstein