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(Hypertension. 2007;50:786.)
© 2007 American Heart Association, Inc.

XVIIth Scientific Meeting of the Inter-American Society of Hypertension

Role of Exercise Training in Cardiovascular Autonomic Dysfunction and Mortality in Diabetic Ovariectomized Rats

Silvia B.C. Souza; Karin Flues; Janaina Paulini; Cristiano Mostarda; Bruno Rodrigues; Leandro E. Souza; Maria-Cláudia Irigoyen; Kátia De Angelis

From the Hypertension Unit (S.B.C.S., K.F., J.P., C.M., B.R., L.E.S., M.-C.I.), Heart Institute (InCor), University of São Paulo Medical School, São Paulo, Brazil; Human Movement Laboratory (K.D.A.), São Judas Tadeu University, São Paulo, Brazil; and the Nephrology Department (S.B.C.S., C.M.), Federal University of São Paulo, São Paulo, Brazil.

Correspondence to Kátia De Angelis, Human Movement Laboratory, São Judas Tadeu University, Av Taquari, 546, São Paulo, São Paulo, Brazil 03166-000. E-mail prof.kangelis{at}usjt.br

Diabetes and menopause markedly increase the risk of cardiovascular disease in women. The objective of the present study was to investigate the effects of exercise training on cardiovascular autonomic dysfunction and on total mortality in diabetic female rats undergoing ovarian hormone deprivation. Female Wistar rats were divided into ovariectomized groups: sedentary and trained controls and sedentary and trained diabetic rats (streptozotocin, 50 mg/kg IV). Trained groups were submitted to an exercise training protocol on a treadmill (8 weeks). The baroreflex sensitivity was evaluated by heart rate responses to arterial pressure changes. Heart rate variability was determined using the SD of the basal heart rate. Vagal and sympathetic tonus were evaluated by pharmacological blockade. Diabetes impaired baroreflex sensitivity (55%), vagal tonus (68%), and heart rate variability (38%). Exercise training improved baroreflex sensitivity and heart rate variability in control and diabetic groups in relation to their sedentary groups. Trained control rats presented increased vagal tonus compared with that of sedentary ones. The sympathetic tonus was reduced in the trained diabetic group as compared with that of other studied groups. Significant correlations were obtained between heart rate variability and vagal tonus with baroreflex sensitivity. Mortality, assessed during the training period, was reduced in trained diabetic (25%) rats compared with mortality in sedentary diabetic rats (60%). Together, these findings suggest that decreases in baroreflex sensitivity and heart rate variability may be related to increased mortality in female diabetic subjects and that improved autonomic regulation induced by exercise training may contribute to decreased mortality in this population.

Key Words: exercise training • autonomic function • mortality • menopause • diabetes