Role of Angiotensin-(1-7) in Rostral Ventrolateral Medulla in Blood Pressure Regulation via Sympathetic Nerve Activity in Wistar-Kyoto and Spontaneous Hypertensive Rats

Angiotensin (Ang)-(1-7) Ang-(1-7) is formed from angiotensin II by angiotensin-converting enzyme 2 (ACE2) and modulates the renin-angiotensin system. We evaluated whether the Ang-(1-7)-Mas axis in the rostral ventrolateral medulla (RVLM) contributes to neural mechanisms of blood pressure (BP) regulation. We microinjected Ang-(1-7), Ang-(1-7)-Mas receptor antagonist A-779, and ACE2 inhibitor DX600 into the RVLM of anesthetized Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHRs). Unilateral Ang-(1-7) microinjection induced a significantly greater increase in AP (arterial blood pressure) in SHR than in WKY. Bilateral A-779 microinjection induced a significantly greater decrease in AP and renal sympathetic nerve activity in SHR than in WKY. Bilateral DX600 microinjection induced a significantly greater decrease in AP in SHR than in WKY. Our results suggest that endogenous Ang-(1-7) in the RVLM contributes to maintain AP and renal sympathetic nerve activity both in SHR and WKY and that its activity might be enhanced in SHR.