Segel L D, Mason D T
Cardiovasc Res. 1982 Jan;16(1):34-9. doi: 10.1093/cvr/16.1.34.
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.
研究了慢性酒精中毒大鼠和对照大鼠心脏β-肾上腺素能受体的特性，以确定受体的改变是否导致离体工作的酒精中毒大鼠心脏对β-肾上腺素能刺激的反应性降低。通过（-）[3H]二氢阿普洛尔结合在粗膜部分评估的受体，与对照大鼠（25.9±1.3 fmol·mg蛋白-1；Kd = 0.55±0.04 nmol·L-1；n = 7）相比，酒精中毒大鼠的受体数量或亲和力均无显著差异（22.5±1.9 fmol·mg蛋白-1；Kd = 0.49±0.03 nmol·L-1；n = 7）。竞争实验表明，（-）异丙肾上腺素对酒精中毒大鼠和对照大鼠心脏受体的结合亲和力没有差异，（-）普萘洛尔对酒精中毒大鼠和对照大鼠心脏受体的亲和力也没有差异。在5'-鸟苷酰亚胺二磷酸存在下，（-）异丙肾上腺素对受体的亲和力在酒精中毒大鼠和对照大鼠心脏中降低的量相同。这些结果表明，慢性酒精中毒大鼠心脏的β-肾上腺素能亚敏感性是由β-肾上腺素能受体或受体与腺苷酸环化酶之间偶联的直接改变以外的生化机制介导的。
