Angiotensin II receptors in cardiac left ventricles of Dahl rats.
1. Dahl Iwai salt-sensitive (DS) rats have been reported as becoming hypertensive 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 angiotensin II (AngII) type 1 and type 2 receptors (AT1 and AT2, respectively) in LVH, we compared cardiac AT1 and AT2 receptors in 10-week-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 diet (0.3 or 8% NaCl, respectively) for 4 weeks. Left ventricular AngII receptors were measured by radioligand binding assays using [125I]-[Sar1,Ile8]-AngII in plasma membrane fractions from these four groups. The AT1 and AT2 receptors were distinguished using their specific 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 Bmax for AT1 and AT2 receptors nor Kd for [125I]-[Sar1,Ile8]-AngII differed between the groups. These results are different from those of other reports of pressure-overload LVH, such as spontaneously hypertensive rats or renovascular hypertension rats, in which AT1 and AT2 receptors were reported to be up-regulated.
Sumida
Y
Y
Department of Internal Medicine II, Yokohama City University School of Medicine, Yokohama, Japan.
Umemura
S
S
Kobayashi
S
S
Kihara
M
M
Tamura
K
K
Ishigami
T
T
Ochiai
H
H
Chiba
E
E
Nyui
N
N
Ishii
M
M
D000818:Animals; D001667:Binding, Competitive; D001794:Blood Pressure / Q000187:drug effects; D006973:Hypertension / Q000150:complications / Q000378:metabolism*; D017379:Hypertrophy, Left Ventricular / Q000150:complications / Q000378:metabolism*; D008297:Male; D051381:Rats; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D011945:Receptors, Angiotensin / Q000187:drug effects / Q000378:metabolism*; D012982:Sodium, Dietary / Q000008:administration & dosage / Q000494:pharmacology; D015854:Up-Regulation
D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D011945:Receptors, Angiotensin; D012982:Sodium, Dietary