Effects of exercise training in hemodynamic profile of diabetics ovariectomized rats. / Efeito do Treinamento Físico no Perfil Hemodinâmico de Ratas Diabéticas Ooforectomizadas.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

Diabetes and menopause markedly increase the risk of cardiovascular disease among women. The objective of the present study was to investigate the effects of exercise training on cardiovascular autonomic dysfunction and in the incidence of mortality in diabetic female rats submitted to ovarian hormones deprivation. Female Wistar rats were divided in ovariectomized groups: sedentary and trained (SO) controls (TO), and sedentary (SDO) and trained diabetics (TDO). Diabetes was induced by a single streptozotocin injection (50 mg/kg i.v.) 15 days after ovariectomy. Arterial pressure (AP), heart rate (HR), heart rate variability (HRV), baroreflex sensitivity and autonomic control of HR were evaluated after the exercise training period on treadmill, started 1 week after ovariectiomy. SO group presented highest body weight at the end of the protocol (3467g) and also highest mean AP (1243 mmHg) and HR (36113 bpm) in relation to other studied groups. OT group showed reduced body weight (3257g), mean AP (1132 mmHg) and HR (3275 bpm) as compared to OS group. DSO animals presented reduced body weight (1867g), bradycardia (2518 bpm) and hypotension (1022 mmHg) when compared to OS animals. TDO rats showed attenuation of these alterations. Diabetes impaired baroreflex sensitivity (~55%). Exercise training induced an improvement in bradycardic and tachycardic responses in controls (~40 and 74%) and diabetic (~89 and 74%) groups in relation to their respective sedentary groups. Heart rate variability was reduced in sedentary diabetic rats (131.3 bpm) when compared to sedentary rats (181.5 bpm). Trained groups showed an increase in heart rate variability (231 and 211.2 bpm in trained diabetic group) as compared with sedentary groups. Diabetes reduced vagal tonus (~68%). Trained diabetic group presented similar vagal tonus than sedentary control and reduced sympathetic tonus when compared to others studied groups. IHR was reduced in SDO rats in relation to SO rats and exercise training attenuated this dysfunction. Correlation analysis showed a relationship between heart rate variability and vagal tonus with bradycardic (r=-0.5 and r=-0.5) and with tachycardic (r=0.6 and r=0.6) responses to AP changes. Mortality was 50% and 25 % among sedentary and trained diabetic animals, respectively. Together these findings may provide insight that baroreflex sensitivity and heart rate variability impairments are potential mechanisms responsible for the enhanced CVD-related mortality observed in diabetic women, as well as, that exercise training-induced autonomic improvement can lower the incidence of mortality in diabetic postmenopause women.

ASSUNTO(S)

1. ovariectomy 2. diabetes nefrologia 1. ovariectomy 2. diabetes 3. barorreflexo 4. variabilidade da freqüência cardíaca

ACESSO AO ARTIGO

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