Key result
Chronic alcohol consumption does not alter cardiac beta-adrenergic receptor number or affinity in rats.
Why the study?
Alterations in cardiac beta-adrenergic receptors may contribute to decreased responsiveness of chronic alcoholic rat hearts to beta-adrenergic stimulation.
Absolute Event Rate: 22.5% vs 25.9%
p-value: p=not significant
The decreased responsiveness of chronic alcoholic rat hearts to beta-adrenergic stimulation is likely mediated by mechanisms other than direct alterations of the beta-adrenergic receptor or its coupling to adenylate cyclase.
Supports post-receptor mechanisms for alcohol-induced cardiac hyporesponsiveness in rats; leaves open human relevance.
Properties of cardiac beta-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 beta-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 he 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 beta-adrenergic subsensitivity of chronic alcoholic rat hearts is mediated by a biochemical mechanism other than a direct alteration of the beta-adrenergic receptor or coupling between the receptor and adenylate cyclase.
No takes yet. Share an insight, caveat, or question.
Segel et al. (1982) studied Chronic alcoholism (animal model) (n=14). Chronic alcohol consumption vs. Control rats was evaluated on Beta-adrenergic receptor number (p=not significant). Chronic alcohol consumption in rats did not significantly alter the number (22.5 vs 25.9 fmol/mg protein) or affinity of cardiac beta-adrenergic receptors compared to controls.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: