ANGIOTENSIN-II RECEPTORS IN CARDIAC LEFT-VENTRICLES OF DAHL RATS

1. Dahl Iwai salt-sensitive (DS) rats have been reported as becoming h ypertensive with left ventricular hypertrophy (LVH) and heart failure when on a high-salt diet, Their circulating renin-angiotensin system ( RAS) has been reported to be suppressed, To evaluate the role of angio tensin II (AngII) type 1 and type 2 receptors (AT(1) and AT(2), respec tively) in LVH, we compared cardiac AT(1) and AT(2) receptors in 10-we ek-old DS rats and Dahl Iwai salt-resistant (DR) rats, 2. Seven pairs of 6-week-old male DS and DR rats were fed either a low-or high-salt d iet (0.3 or 8% NaCl, respectively) for 4 weeks, Left ventricular AngII receptors were measured by radioligand binding assays using [I-125]-[ Sar(1),Ile(8)]-AngII in plasma membrane fractions from these four grou ps, The AT(1) and AT(2) receptors were distinguished using their speci fic antagonists CV 11974 and PD 123319, respectively, 3. The high-salt diet increased blood pressure and the left ventricle:bodyweight ratio in DS rats, However, neither B-max for AT(1) and AT(2) receptors nor K-d for [I-125]-[Sar(1),Ile(8)]-AngII differed between the groups, The se results are different from those of other reports of pressure-overl oad LVH, such as spontaneously hypertensive rats or renovascular hyper tension rats, in which AT(1) and AT(2) receptors were reported to be u p-regulated.