title: Vascular angiotensin II receptors in renal and DOCA-salt hypertensive rats.
abstract: To determine the contribution of receptor number and affinity to changes in vascular reactivity to angiotensin II (AII) in hypertensive rats, we have investigated the binding of 125I-AII to a particulate fraction of the rat mesenteric artery of hypertensive rats. In two-kidney, one clip hypertensive rats, receptor concentration (Bmax) was 83 +/- 13 fmol/mg and the dissociation constant (Kd) 0.6 +/- 0.1 nM vs 75 +/- 5.3 fmol/mg and 0.6 +/- 0.1 nM in normotensive controls, although PRA was much higher in the former. Bmax was reduced in these hypertensive rats after sodium depletion, as in normal rats. One-kidney, one clip hypertensive rats (Bmax 88 +/- 17 fmol/mg, Kd 0.6 +/- 0.1 nM) did not differ from uninephrectomized control rats (96 +/- 9 fmol/mg, Kd 0.5 +/- 0.1 nM). In DOCA-salt hypertensive rats, binding capacity was increased (125 +/- 2 fmol/mg, Kd 0.7 +/- 0.0 nM) vs uninephrectomized salt-loaded rats (Bmax 95 +/- 6 fmol/mg, Kd 0.6 +/- 0.1 nM), although PRA was suppressed comparably in both groups. The salt-loaded rats did not differ from uninephrectomized controls drinking water. We conclude that changes in the circulating renin-angiotensin system do not explain all the variations in receptor number in hypertensive rats. Our results suggest a role of mineralocorticoids in the regulation of vascular AII receptors.
mesh_terms: D000450:Aldosterone / Q000097:blood; D000804:Angiotensin II / Q000032:analysis* / Q000502:physiology; D000818:Animals; D001665:Binding Sites; D003900:Desoxycorticosterone; D006973:Hypertension / Q000139:chemically induced / Q000503:physiopathology*; D006977:Hypertension, Renal / Q000503:physiopathology*; D006978:Hypertension, Renovascular / Q000503:physiopathology; D008297:Male; D008638:Mesenteric Arteries / Q000032:analysis; D009131:Muscle, Smooth, Vascular / Q000032:analysis*; D051381:Rats; D011919:Rats, Inbred Strains; D011945:Receptors, Angiotensin / Q000032:analysis* / Q000502:physiology; D011956:Receptors, Cell Surface / Q000032:analysis*; D012083:Renin / Q000097:blood; D012965:Sodium Chloride
chemical_list: D011945:Receptors, Angiotensin; D011956:Receptors, Cell Surface; D000804:Angiotensin II; D003900:Desoxycorticosterone; D012965:Sodium Chloride; D000450:Aldosterone; D012083:Renin