Alterations of Binding Characteristics of α_1-, β_1-Adrenoceptors and Ca^<2+> Binding Sites in the Myocardium of Spontaneously Hypertensive Rats (SHR) by Chronically Administered Bunazosin, Atenolol, Ketanserin and Verapamil

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The effects of chronic treatment with bunazosin, atenolol, ketanserin and verapamil on the myocardium of the spontaneously hypertensive rat (SHR) were examined by the radioligand binding assay method using [^3H]prazosin, [<125>I]iodocyanopindolol and [^3H]nitrendipine binding to α_1- and β_1-adrenergic receptors and Ca^<2+> binding sites. The norepinephrine concentration in the rat myocardium was also determined. (1) All of these drugs lowered the elevated blood pressure of the SHR. (2) Only ketanserin administration increased the K_d value of the α_1-adrenoceptor in the SHR. (3) Administration of atenolol and ketanserin to the SHR decreased the B_<max> value of the β_1-adrenoceptor. (4) Verapamil, bunazosin and atenolol also lowered the B_<max> values of the Ca^<2+> binding sites of SHRs. (5) All drugs except for atenolol lowered the norepinephrine concentration in the myocardium of the SHR. These findings suggest that the SHR has an abnormality of the α_1 and β_1-adrenoceptors and Ca^<2+> binding site of the myocardium, that the drugs had a beneficial effect on these receptors, that the drugs could also lower the high norepinephrine content in the myocardium of the SHR and that some of these drugs also affected the binding characteristics of other types of membrane receptors.
社団法人日本薬学会の論文
1993-05-15