Responses of the systemic and local vascular renin‐angiotensin systems to chronic aerobic exercise training in an angiotensin II infusion model of hypertension

Abstract

The renin-angiotensin system (RAS) plays a major role in the pathophysiology of hypertension. In addition, chronic aerobic exercise training is known to improve vasomotor function in various models of hypertension. Thus, we investigated the responses of components from the systemic and local vascular RAS to chronic exercise training in an angiotensin II (AII) infusion model of hypertension. Male Sprague-Dawley rats were exercised trained (EX) for 6 weeks or restricted to cage-bound activity (SED). Osmotic mini-pumps facilitated infusion of AII (0.17mg/day) or vehicle saline (SL) for 3 or 8 days. Plasma AII levels decreased for SED AII-infused rats (Day 3: 24.41±5.62pg/mL; Day 8: 9.08±4.83pg/mL) compared to SED SL-infused rats (Day 3: 55.17±0.32pg/mL; Day 8: 55.4±0.55pg/mL) (p<0.01). EX AII-infused rats showed further lowering of plasma AII levels after 3 days (12.4±3.38pg/mL, p<0.01), but not after 8 days. However, an upregulation of ACE protein (+74%) was observed in the abdominal aorta after 8 days of AII-infusion compared to SL-infusion (p<0.05); exercise did not affect this response. MAP increased in SED AII-infused rats (Day 3: 174±2mmHg; Day 8: 194±6mmHg) compared to SED SL-infused rats (Day 3: 127±1mmHg; Day 8: 120±3mmHg) (p<0.01). The present study suggests that both AII-infusion and chronic exercise training affect the systemic and local vascular RAS. Funding: Heart and Stroke Foundation of Ontario