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Abstract: SA-PO1094

Voluntary Exercise Decreases Blood Pressure, Angiotensin II, and Aldosterone without Changing Glomerular Filtration Rate in Two-Kidney One-Clip Hypertensive Rats

Session Information

Category: Hypertension

  • 1101 Hypertension: Basic and Experimental - Neural and Inflammatory Mechanisms

Authors

  • Waldman, Brian M, Wayne State University, Detroit, Michigan, United States
  • Augustyniak, Robert A, Wayne State University, Detroit, Michigan, United States
  • Chen, Haiping, Wayne State University, Detroit, Michigan, United States
  • Rossi, Noreen F., Wayne State University, Detroit, Michigan, United States
Background

Voluntary dynamic exercise promotes sympathoinhibition and decreases blood pressure in two-kidney one-clip (2K1C) rats, a model of renovascular hypertension. Renal sympathetic nerves increase renin secretion and tubular sodium (Na+) reabsorption. We hypothesized that daily spontaneous wheel running exercise by 2K1C rats will decrease mean arterial pressure (MAP), plasma angiotensin II (Ang II) and aldosterone (Aldo), and normalize urinary Na+ and potassium (K+) excretion independent of glomerular filtration rate (GFR).

Methods

Five week-old male Sprague Dawley rats underwent sham clipping (Sham) or right renal artery clipping (2K1C). Rats were randomly assigned to standard caging (SED) or cages with access to running wheels (EX). After 12 weeks, rats were assigned to 1) collection of aortic blood for measurement of Ang II and Aldo or 2) assessment of inulin clearances and excretory function.

Results

Running distances were comparable in both EX groups. MAP was lower in 2K1C EX vs 2K1C SED rats (191±4 vs 169±2 mmHg; P<0.05). Elevated plasma Ang II in 2K1C SED rats (187.4±43.6 fmol/ml) was lower in 2K1C EX rats (48.9±7.5 fmol/ml; P<0.05) which did not differ from Sham SED or Sham EX rats (29.3±8.1 and 47.3±7.1 fmol/ml). Aldo levels paralleled those of Ang II. Clipped kidney weights were significantly lower in both 2K1C groups (P<0.05), but GFR and urine flow rates were no different from right and left kidneys among the four groups. Total and fractional Na+ excretion from the unclipped kidney of 2K1C SED rats was higher vs either Sham group (P<0.05). Values in 2K1C EX rats were similar to the Sham groups. Total and fractional K+ excretion was higher from the unclipped kidney of 2K1C SED rats (P<0.05); results of exercise paralleled those of Na+ excretion.

Conclusion

These findings show that voluntary dynamic exercise, known to promote renal sympathoinhibition, lowers blood pressure and decreases plasma Ang II and Aldo levels in the 2K1C model of renovascular hypertension without deleterious effects on GFR. The effects on Na+ excretion underscore the impact of pressure natriuresis despite elevated plasma Ang II and Aldo in sedentary 2K1C rats. In contrast, K+ excretion appears to be primarily regulated by circulating Aldo levels and distal Na+ delivery.

Funding

  • Veterans Affairs Support