Effect of aerobic exercise training on renal responses to sodium in hypertensives.
BACKGROUND
Aerobic exercise training has been shown to improve cardiovascular function and lower blood pressure (BP) in older adults. The exact mechanism(s) by which aerobic exercise training elicits these changes are unknown; however, it is possible that changes in renal hemodynamics may play a role.


OBJECTIVE
The present study was undertaken to examine the effect of aerobic exercise training on renal hemodynamics in older hypertensive individuals.


METHODS
Renal plasma flow (RPF) and glomerular filtration rate (GFR) were determined by plasma and urinary clearances of 131I-hippuran and 99mTc-DTPA after 8 d of low (20 mEq) and high (200 mEq) Na+ diets in 31 older (63 +/- 1 yr), hypertensive (152 +/- 2/88 +/- 1 mm Hg) individuals at baseline and following 6 months of aerobic exercise training (at 75% VO2max, three times a week, 40 min per session).


RESULTS
Following 6 months of aerobic exercise training, a significant increase was seen in maximal aerobic capacity (VO2max: 18.3 +/- 0.7 vs 20.7 +/- 0.7 mL.kg.min(-1), P = 0.017) as well as a significant decrease in resting systolic (152 +/- 2 vs 145 +/- 2 mm Hg, P = 0.037) and mean arterial (109 +/- 1 vs 105 +/- 1 mm Hg, P = 0.021) BP. No significant (P < 0.05) effects were seen of aerobic exercise training on RPF (208.8 +/- 12.2 vs 197.1 +/- 13.1 mL.min(-1).1.73 m(-2)), GFR (68.9 +/- 3.6 vs 69.0 +/- 3.9 mL.min(-1).1.73 m(-2)), or filtration fraction (35.3 +/- 2.3 vs 37.1 +/- 2.4%) on the low Na+ diet or RPF (210.6 +/- 12.8 vs 212.1 +/- 11.7 mL.min(-1).1.73 m(-2)), GFR (72.9 +/- 4.1 vs 77.3 +/- 4.3 mL.min(-1).1.73 m(-2)), or filtration fraction (37.1 +/- 2.5 vs 37.7 +/- 3.0%) on the high Na+ diet.


CONCLUSIONS
Our results suggest that changes in renal hemodynamics do not contribute to the reduction in resting BP in older hypertensive persons.
Dengel
Donald R
DR
School of Kinesiology, University of Minnesota, Minneapolis, MN 55455, USA. denge001@umn.edu
Brown
Michael D
MD
Reynolds
Thomas H
TH
Supiano
Mark A
MA
D000704:Analysis of Variance; D005260:Female; D005919:Glomerular Filtration Rate; D006439:Hemodynamics; D006801:Humans; D006973:Hypertension / Q000503:physiopathology* / Q000628:therapy*; D007668:Kidney / Q000503:physiopathology*; D007677:Kidney Function Tests; D008297:Male; D008875:Middle Aged; D010806:Physical Education and Training; D012079:Renal Circulation / Q000502:physiology; D012964:Sodium / Q000378:metabolism*
D012964:Sodium