¹Department of Internal Medicine III, Kurume University School of Medicine, Fukuoka, Japan.

Correspondence: Hidehiro Matsuoka, MD, PhD, Department of Internal Medicine III, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka 830, Japan.

^*This study was supported in part by grants from Grant-in-Aid for Scientific Research #2-635-6039-07770547 and #2-635-7036-08770533 from the Ministry of Education, Science and Culture, Japan and a grant from Kimura Memorial Heart Foundation, Kurume.

Received 31 July 1996; Revised  0000; Accepted 10 February 1997.

Abstract

To clarify characteristics of the patients in whom exercise training lowers blood pressure and to elucidate the mechanisms by which exercise training lowers blood pressure, we evaluated 24-h blood pressure, glomerular filtration rate (GFR), renal blood flow (RBF), filtration fraction (FF), plasma renin activity (PRA), plasma aldosterone concentration (PAC), plasma norepinephrine concentration (PNE), and incremental area of insulin/glucose (I/G) during 75 g oral glucose tolerance test, and assessed arterial baroreceptor function (BSI) before and after a 3-week exercise training program (four 6-min sessions daily at 75% O₂ max). Patients were classified as responders (n = 15) if they showed statistically significant reduction in the multiple comparison of 24-h mean arterial pressure (MAP), or as nonresponders (n = 15) if they did not. Although there were no significant differences between responders and nonresponders in age, weight, MAP, GFR, RBF, RPF, FF, PNE, I/G, or BSI before exercise, renal vascular resistance (RVR; P < .05), PRA (P < .05), and PAC (P < .05) were significantly higher in responders than in nonresponders. The fractional excretion of sodium (FENa) (P < .05) were significantly lower in responders than in nonresponders. After exercise training, FF (P < .01), RVR (P < .05), PNE (P < .05) PRA (P < .01), and I/G (P < .05) decreased significantly only in responders. The decrease in MAP significantly correlated with the reductions in FF (r = 0.46, P < .05), PNE (r = 0.52, P < .01) and RVR (r = 0.40, P < .05). Thus, in patients who have higher RVR and PRA, exercise training lowered blood pressure in parallel to a reduction in RVR associated with decreases in sympathetic tone and improvement of insulin resistance. Our results suggest that exercise-induced changes in renal hemodynamics may contribute to the reduction in blood pressure in these patients.