A Method for Studying Isolated Resistance Vessels from Rabbit Mesentery and Brain and Their Responses to Drugs

Abstract

A technique has been developed for studying the reactivity of single, isolated resistance vessels, 50 to 250 µ o.d., perfused at constant flow rate. The validity of the method is established because responses to a given stimulating agent are reproducible and stable over a reasonable period of time. The magnitude of the response is dependent on the perfusion pressure, being maximal at a physiological pressure level. Resistance vessels from mesentery and brain of normal rabbits were compared with respect to their threshold for response to several vasoconstrictors. The results reaffirmed the individuality of smooth muscle from different vascular beds. Cerebral and mesenteric vessels are alike in the dose required for threshold constrictor response to KCl, angiotensin and plasma, but differ in that cerebral vessels have a higher threshold for response to epinephrine, norepinephrine and serotonin, and a lower threshold for response to vasopressin, than mesenteric vessels. Since the differences in threshold between vessels from the two sources are not the same for all stimulating agents, it seems probable that smooth muscle of the cerebral vessels is not generally less sensitive to all stimuli than that of mesenteric vessels, but that vessels from the two sources differ in the "number of receptors" for the several vasoactive agents.