Role of angiotensin-(1-7) in rostral ventrolateral medulla in blood pressure regulation via sympathetic nerve activity in Wistar-Kyoto and spontaneous hypertensive rats.

Nakagaki T, Hirooka Y, Ito K, Kishi T, Hoka S, Sunagawa K.

Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan.

Clin Exp Hypertens. 2011;33(4):223-30. doi: 10.3109/10641963.2011.583967.

   

The Renin-Angiotensin System (RAS) modulates blood pressure, this study focuses upon Angiotensin-(1-7) in the RVLM. The objective of the present study was to determine whether Ang-(1-7) in the RVLM contributes to the maintenance of BP in the rat model of hypertension. Male Wistar-Kyoto rats (WKYs) and spontaneously hypertensive rats (SHRs) used. SHRs and WKYs monitored for BP, HR, and renal sympathetic nerve activity (RSNA). Rats injected with Ang (1-7), Mas receptor antagonist A-779, and ACE2 inhibitor DX600. They also performed Western Blot analysis for Mas receptors in SHR and WKY. Unilaterial Ang-(1-7) microinjection inducted a significantly greater increase in MAP in SHR than WKY. Bilateral A-779 microinjection induced a significantly greater decrease in AP and renal sympathetic nerve activity in SHR than WKY. Bilateral DX600 microinjection induced a significantly greater decrease in AP in SHR than in WKY. These results suggest that endogenous Ang-(1-7) in the RVLM contributes to maintain AP and renal sympathetic nerve activity in both SHR and WKY, and that its activity is likely enhanced in SHR. We could probably do a similar study in WR and SEDs, however, it would probably just lead to a somewhat similar result to this SHR v. WKY study. This study suggests that there is a greater deal of sympathoexcitation for any given input in the case of non-normotensive conditions.

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