Subsensitivity of Cardiac β-Adrenoceptors in Renal Hypertensive Rats

    loading  Checking for direct PDF access through Ovid



β-Adrenoceptors were labeled with the selective β-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 radioligand. The lowered sensitivity to catecholamine is probably due to chronic exposure of β-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 hr for normotensive).

Related Topics

    loading  Loading Related Articles