Subsensitivity of cardiac beta-adrenoceptors in renal hypertensive rats.
beta-Adrenoceptors were labeled with the selective beta-antagonist (-)[3H]dihydroalprenolol ([3H]DHA). Cardiac membranes isolated from renal hypertensive rats had the same density of adrenoceptors as normotensive rats (28 fmoles/mg of protein in both groups) but showed a significant elevation of the dissociation constant for [3H]DHA (Kd = 1.86 nM versus 1.04 nM for controls), indicating a reduced affinity of cardiac adrenoceptors for the radioligant. The lowered sensitivity to catecholamine is probably due to chronic exposure of beta-receptors to a high concentration of noradrenaline, whose turnover in cardiac nerves of renal hypertensive rats was significantly accelerated (turnover time 10.5 hr for hypertensive versus 17.2 for normotensive).
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004082:Dihydroalprenolol; D006321:Heart / Q000187:drug effects*; D006977:Hypertension, Renal / Q000503:physiopathology*; D007700:Kinetics; D008297:Male; D009206:Myocardium / Q000378:metabolism; D009392:Nephrectomy; D051381:Rats; D011941:Receptors, Adrenergic / Q000187:drug effects*; D011943:Receptors, Adrenergic, beta / Q000187:drug effects*
D011941:Receptors, Adrenergic; D011943:Receptors, Adrenergic, beta; D004082:Dihydroalprenolol