Beta-adrenergic receptors in chronic alcoholic rat hearts

• Published in: Cardiovascular research 1982-01, Vol.16 (1), p.34-39
• Main Authors: SEGEL, LEIGH D, MASON, DEAN T
• Format: Article
• Language: English
• Subjects: Alcoholism - metabolism; Animals; beta -adrenergic; Binding, Competitive; ethanol; heart; Humans; Isoproterenol - metabolism; Male; Myocardium - metabolism; Propranolol - metabolism; Rats; Receptors, Adrenergic - analysis; Receptors, Adrenergic, beta - analysis
• ISSN: 0008-6363; 1755-3245
• DOI: 10.1093/cvr/16.1.34

Properties of cardiac β-adrenergic receptors from chronic alcoholic and control rats were studied to determine whether alterations in the receptor contribute to the decreased responsiveness of isolated working alcoholic rat hearts to β-adrenergic stimulation. The receptors, assessed in crude membrane fractions by the binding of (−)[3H]dihydroalprenolol, did not differ significantly in either number or affinity in alcoholic rats (22.5± 1.9 fmol·mg protein−1; KD=0.49 ±0.03 nmol·litre−1; n=7) compared with control rats (25.9±1.3 fmol·mg protein−1; KD=0.55 ±0.04 nmol·litre−1; n=7). Competition experiments indicated that there was no difference in the binding affinity of (−)isoprenaline for the alcoholic and control rat heart receptors, nor in the affinity of (−)propranolol for the alcoholic and control rat heart receptors. In the presence of 5′-guanylylimidodiphosphate, the affinity of (−)isoprenaline for the receptors was decreased the same amount in the alcoholic and control rat hearts. These results suggest that the β-adrenergic subsensitivity of chronic alcoholic rat hearts is mediated by a biochemical mechanism other than a direct alteration of the β-adrenergic receptor or coupling between the receptor and adenylate cyclase.