Effect of castration on renin-angiotensin system of hypertensive rats submitted to chronic hypobaric hypoxia (simulated altitude: 4400 m).

The aim of the present study was to provide an overview of the role of circulating gonadal steroids on the adaptive changes of the renin-angiotensin system to chronic hypobaric hypoxia (CHH: 4400 m simulated altitude in an hypobaric chamber) and the development of experimental hypertension by bilateral renal ischemia. In order to fulfill this goal, blood pressure (BP), plasma renin activity (PRA) and plasma angiotensinogen concentration (PAoC) as well as haematocrit (Htc) and body weight (BW) of intact and post-puberal castrated normotensive (Nt) and hypertensive (Ht) rats of both sexes were studied following an experimental design similar to that of previous works. Post-puberal castration decreased BP of Nt and Ht rats subjected to CHH. Sexual dimorphism in BP, PRA and PAoC was maintained while that in haematocrit disappeared after castration. Results suggest that circulating sexual steroid hormones are involved in the response of the renin-angiotensin system to the experimental conditions of environmental reduced O2 partial pressure.