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KMID : 0377519910160030241
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Chung-Ang Journal of Medicine
1991 Volume.16 No. 3 p.241 ~ p.254
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A Study on β-adrenergic Receptors in Rat Cardiac Membranes by[³H] Dihydroalprenolol
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Abstract
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The,catecholamines are key regulators of many physiologic events in human beings. These catecholamine initiate target-cell response by binding to specific recognition sites, the adrenergic receptors. Super-and subsensitivity of the myocardial receptors and their functional status during myocardial failure have important clinical and pharmacological implications.
The development of radioligand binding technique using radioactively labeled hormones or drugs, either agonists or antagonists, opened the new era of receptor investigation.
(´H) Dihydroalprenolol was used to identify the veta-adrenergic receptors of rat cardiac membranes in this study. .
The concentration dependence of (3H) Dihydroalprenolol binding was studied with labeled compounds of various concentrations ranging from 5x 10-" M to 1.5x-8M.
Specific (3H) Dihydroalprenolol binding was a saturable process and Scatchard analysis of the data showed a single class of binding sites characterized by an equilibrium dissociation constant Kd of 5.2x 10 9 M and ´a calculated Bmax of about 68.8 fmol/mg protein.
The specific binding occurred as rapidly and reversibly as the response to the unlabeled ligand and it increased as a linear function of increasing tissue concentration.
Levo epinephrine was more potent than levo norepinephrine in inhibiting (H )l Dihydroalprenolol binding.
The use of (3H) Dihydroalprenolol to identify beta-adrenergic receptors will make possible the study of alterations in number and affinity of cardiac beta-receptors in m2aiy clinical states of altered sensitivity to catecholamines.
(Key Words Beta adrenergic receptor, Rat cardiac membrane, (3H) Dihydroalprenolol binding)
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