Selective Increase in Renal Arcuate Innervation Density and Neurogenic Constriction in Chronic Angiotensin II-Infused Rats

ABSTRACT—This study investigated the effects of angiotensin II “slow pressor” hypertension on structure and function of nerves supplying the renal vasculature. Low-dose angiotensin II (10 ng/kg per minute, initially sub-pressor) or saline vehicle was infused intravenously for 21 days in rats, and the effects were compared in renal and mesenteric arteries. Mean arterial pressure averaged 12±2 mm Hg higher than in vehicle-infused rats at 21 days. Using electron microscopy, the innervation density of renal arcuate, but not mesenteric arteries of equivalent size, was significantly higher in angiotensin II-infused than in vehicle-infused rats. Functional testing on a pressure myograph revealed that constrictions evoked by nerve stimulation in arcuate arteries were 2.3±0.7-fold greater in vessels from angiotensin II-infused compared with vehicle-infused rats (P