Hemodynamic effects of activation of renal and mesenteric sensory nerves in rats

Afferent nerves from the kidney and mesentery reflexly influence the cardiovascular system when activated. To examine the specificity of these reflexes, comparisons were made of the regional hemodynamic responses elicited by intra-arterial infusion of various agents into the renal (ir) and mesenteric (im) circulation. Experiments were performed in conscious rats, chronically instrumented with Doppler flow probes. Local ir as well as im infusions of bradykinin caused a hemodynamic reflex pattern characterized by a dose-dependent increase in arterial pressure, heart rate, and resistance in the renal and mesenteric vascular beds, whereas hindquarter resistance did not change. Similar hemodynamic reflex patterns were evoked by ir and im infusions of adenosine and 5-hydroxytryptamine. Thus neither application of different chemicals nor their route of infusion resulted in qualitatively different hemodynamic reflex patterns. This suggests that afferent nerve fibers from the kidney and mesentery share a common physiological function.