Role of renin-antiotensin-system and simpathetic nervous system in dexamethasone-induced hypertension: preventive effects of exercise training

Abstract

Synthetic glucocorticoids are widely used nowadays in order to treat inflammation and allergies. However, the chronic use may determine metabolic and haemodynamic alterations causing diabetes, dyslipidemia and hypertension. It has been shown that the excess of glucocorticoids causes increases in blood pressure, however, the mechanisms responsible by this effect are not completely known. It is known that renin-angiotensin system (RAS) and sympathetic nervous system (SNS) contribute to the development/maintenance of essential hypertension in men and in different experimental models of hypertension. Aerobic exercise, on the other hand, is used as part of treatment since it promotes central and peripheral adaptive responses. We have shown that pre-physical conditioning attenuates high level of blood pressure, as well as hyperglycemia and hiperinsulinemia followed by dexamethasone treatment (Amaral et a, 2010 and Barel et al, 2010). However, almost nothing is known about the role of RAS and SNS on hypertension induced by dexamethasone. This work investigates if the mechanisms induced by exercise training to decrease blood pressure involve the RAS and/or SNS. Wistar rats, sedentary and trained, treated or not, will be used. After the determination of fasting glycemia, basal blood pressure and the response to hexamethonium, the rats will be anesthetized in order to have their skeletal and cardiac muscles harvested and processed for genes and protein related to the RAS determination. (AU)