Exercise training improves arterial baro- and chemoreflex in control and diabetic rats

Abstract

We investigated the effect of exercise training on blood pressure, heart rate, and arterial baro- and chemoreflex sensitivity in diabetic rats (streptozotocin, 50 mg/kg iv). Male Wistar rats (251 ± 10 g) were divided into 4 groups ( n = 8, each group): sedentary normotensive (SC), sedentary diabetic (SD), trained normotensive (TC), and trained diabetic (TD). Trained groups underwent exercise training on a treadmill (10 weeks). Exercise training induced resting bradycardia (340 ± 5 vs. 316 ± 8 bpm) and improvement in baroreflex tachycardic response (3.4 ± 0.31 vs. 2.7 ± 0.06 bpm/mmHg in SC) and chemoreflex bradycardic (145 ± 12 vs. 78 ± 7 bpm in SC) and pressor (49 ± 5 vs. 22 ± 3 mmHg in SC) responses in control rats. Diabetic-induced hypotension (SC: 107 ± 2 vs. SD: 93 ± 2 mmHg) and bradycardia (SC: 340 ± 5 vs. SD: 276 ± 7 bpm) were reversed by exercise training. Baroreflex tachycardic and bradycardic responses impaired in SD rats (SD: 2.1 ± 0.18 and 1.3 ± 0.08 vs. SC: 2.7 ± 0.06 and 1.3 ± 0.08 bpm/mmHg) were enhanced in TD rats (2.5 ± 0.1 and 1.7 ± 0.06 bpm/mmHg). Chemoreflex bradycardic and pressor responses, attenuated in SD rats (23 ± 9 bpm and 7 ± 1 mmHg) in relation to SC rats, were improved by exercise (TD: 84 ± 15 bpm and 32 ± 5 mmHg). The improvement in arterial baro- and chemoreflex-mediated control of circulation in trained control and diabetic rats reinforces the role of exercise in the management of cardiovascular risk in healthy and diabetic individuals.