Renal nerve responses to cardiac receptor stimulation with bradykinin in monkeys

Previous data from our laboratory demonstrated a species difference between the cat and dog in the arterial blood pressure (ABP) and renal nerve activity (RNA) responses to epicardial bradykinin (BK) applications. The present study was carried out to determine the ABP and renal nerve responses to chemical activation of cardiac afferents by BK in the intact and sinoaortic-denervated and vagotomized (SAD + Vx) nonhuman primate. Seven Macaque monkeys (fascicularis and nemestrina) anesthetized with pentobarbital or chloralose were used in this study. The heart was exposed and suspended in a pericardial cradle. A left atrial (LA) catheter was inserted through the appendage. Changes in ABP and RNA (percent change from control) were determined when 1 and 10 μg/ml BK (in 1-ml volume) were applied to the anterior surface of the left ventricle or injected into the LA (0.3 and 3.0 μg/kg BK) in the intact and SAD + Vx state. In both the intact and SAD + Vx monkeys, ABP and RNA were significantly reduced with epicardial BK. In the intact state, LA injections of BK produced a significant decrease in the % Δ of RNA and a depressor response. In the SAD + Vx monkey, significant hypotensive responses were also observed with LA injections of BK concomitant with significant reductions in RNA. These results show the existence of a depressor response and inhibition of renal sympathetic nerve activity in the nonhuman primate mediated by the action of bradykinin on cardiac sympathetic afferents.