The present study was performed to evaluate renal vascular responsiveness (RVR) to ANG II in hypertensive transgenic rats [TGR; strain TGR(mRen2)27] harboring the mouse ren-2 renin gene. Renal blood flow (RBF) responses to either intravenous or intrarenal arterial administration of ANG II were assessed in pentobarbital sodium-anesthetized female heterozygous TGR (9-12 wk old) and age-matched transgene-negative Hanover Sprague-Dawley rats (HanSD). Intravenous bolus injections of 15 and 30 ng ANG II elicited dose-dependent increases in mean arterial blood pressure (AP) and decreases in RBF in both TGR and HanSD. However, the magnitude of the increases in AP was greater in TGR than in HanSD (24 ± 1 vs. 17 ± 2 mmHg and 33 ± 2 vs. 25 ± 1 mmHg, respectively, P < 0.05 in both cases). Similarly, the magnitude of the decrease in RBF elicited by intravenous administration of 15 ng of ANG II was greater in TGR than HanSD (62 ± 3 vs. 52 ± 5%, P < 0.05). Intrarenal arterial administration of 1.5 and 3 ng ANG II did not alter mean AP in either group but elicited larger decreases in RBF in TGR than in HanSD (24 ± 2 vs. 13 ± 1% and 41 ± 5 vs. 30 ± 2%, respectively, P < 0.05 in both cases). In contrast, intrarenal arterial administration of norepinephrine (40 and 80 ng) elicited smaller decreases in RBF in TGR than in HanSD (24 ± 3 vs. 40 ± 6% and 51 ± 9 vs. 71 ± 8%, respectively, P < 0.05 in both cases), indicating that TGR do not exhibit a generalized increase in RVR to endogenous vasoconstrictors. Furthermore, the enhanced RVR to ANG II does not appear to reflect an impaired RVR to endogenous vasodilator factors since intrarenal administration of bradykinin and acetylcholine elicited larger increases in RBF in TGR than in HanSD. The present findings indicate that hypertensive TGR exhibit exaggerated renal and peripheral vascular responses to ANG II, which likely contributes to an increased renal and peripheral vascular resistance and thereby to the hypertension in TGR.

acetylcholine; arterial blood pressure; bradykinin; endothelium-dependent vasodilators; hypertension; norepinephrine; renal blood flow; renal hemodynamics; renal vascular resistance

This article has been cited by other articles:

				E. Joly, R. Seqqat, B. Flamion, N. Caron, A. Michel, J. D. Imig, and R. Kramp Increased renal vascular reactivity to ANG II after unilateral nephrectomy in the rat involves 20-HETE Am J Physiol Regulatory Integrative Comp Physiol, October 1, 2006; 291(4): R977 - R986. [Abstract] [Full Text] [PDF]

				D. ALBRECHT, T. NITSCHKE, and O. VON BOHLEN UND HALBACH Various effects of angiotensin II on amygdaloid neuronal activity in normotensive control and hypertensive transgenic [TGR(mREN-2)27] rats FASEB J, May 1, 2000; 14(7): 925 - 931. [Abstract] [Full Text]