ABSTRACT
Spontaneous dynamic exercise promotes sympathoinhibition and decreases arterial pressure in two-kidney, one-clip (2K-1C) hypertensive rats. Renal sympathetic nerves stimulate renin secretion and increase renal tubular sodium reabsorption. We hypothesized that daily voluntary wheel running exercise by 2K-1C rats will decrease mean arterial pressure (MAP), plasma angiotensin II (Ang II), and aldosterone as well as normalize urinary sodium and potassium excretion independent of changes in glomerular filtration rate (GFR). Five-week-old male Sprague Dawley rats underwent sham clipping (Sham) or right renal artery clipping (2K-1C). Rats were randomized to standard caging (SED) or cages with running wheels (EX). After 12 weeks, rats were assigned to either collection of aortic blood for measurement of Ang II and aldosterone or assessment of inulin clearances and excretory function. Running distances were comparable in both EX groups. MAP was lower in 2K-1C EX vs 2K-1C SED rats (P<0.05). Plasma Ang II and aldosterone were significantly higher in 2K-1C SED rats and decreased in 2K-1C EX rats to levels similar to Sham SED or Sham EX rats. Clipped kidney weights were significantly lower in both 2K-1C groups, but GFR and urine flow rates were no different from right and left kidneys among the four groups. Total and fractional sodium excretion rates from the unclipped kidney of 2K-1C SED rats were higher vs either Sham group (P<0.05). Values in 2K-1C EX rats were similar to the Sham groups. Potassium excretion paralleled sodium excretion. These studies show that voluntary dynamic exercise in 2K-1C rats decreases plasma Ang II and aldosterone, which contribute to the lower arterial pressure without deleterious effects on GFR. The effects on sodium excretion underscore the impact of pressure natriuresis despite elevated plasma Ang II and aldosterone in sedentary 2K-1C rats. In contrast, potassium excretion is primarily regulated by circulating aldosterone and distal sodium delivery.
