Effects of graded changes in reflex renal nerve activity on renal function

Abstract

The effects of reflexly produced graded increases in renal nerve activity on excretion of sodium and potassium, urinary flow, glomerular filtration rate (GFR), renal plasma flow (RPF), renin release, and renal venous norepinephrine (NE) overflow were examined in anesthetized dogs. Renal nerve activity was increased by carotid artery occlusion while renal perfusion pressure was held constant. Linear correlation was determined by plotting the percent change from control for each dependent variable vs. the percent change in mean renal nerve activity (MRNA). The percent changes from control for sodium excretion and urinary flow were negatively correlated with percent change from control in MRNA (P less than 0.01), and the percent change from control for renin release was positively correlated with percent change from control in MRNA (P less than 0.05). NE overflow was observed to increase as renal nerve activity increased. These results indicate that physiologically elicited increases in MRNA from 10 to greater than 100% are significantly correlated with changes in sodium excretion, urine flow, and renin release with little or no measurable change in GFR, RPF, or potassium excretion.