AJP - Heart and Circulatory Physiology, Vol 271, Issue 1 120-H125, Copyright © 1996 by American Physiological Society
Regulation of ANG II receptor in hypertension: role of ANG II
D. H. Wang, A. Yao, H. Zhao and D. J. DiPette
Department of Internal Medicine, University of Texas Medical Branch, Galveston 77555, USA.
To investigate the role of angiotensin II (ANG II) in the development of
hypertension induced by reduced renal mass (RRM) and the gene expression of
ANG II type 1 (AT1) receptors in the remnant renal tissue, four groups of
rats were given 1% NaCl in water and subjected to RRM, RRM+ ramipril, RRM+
losartan, or sham surgery (control). Tail-cuff systolic blood pressure was
significantly higher in RRM rats than in the other three groups. Northern
blot showed that AT1 gene expression was significantly decreased in RRM,
RRM + ramipril, or RRM + losartan vs. control. There was no significant
difference among the three RRM groups. Renal transforming growth
factor-beta 1 (TGF-beta 1) mRNA levels were increased threefold (P <
0.05) in RRM, RRM+ ramipril, and RRM+ losartan vs. control. There was no
significant difference among the three RRM groups. We conclude that the
development of RRM hypertension is ANG II dependent but not mediated by AT1
gene expression. RRM downregulates AT1 mRNA and upregulates TGF-beta 1 mRNA
in the remnant renal tissue, regardless of blood pressure or plasma levels
of ANG II, suggesting that these gene responses are triggered by an effect
of local injury.
