BETA-ADRENERGIC RECEPTOR-G PROTEIN ADENYLATE-CYCLASE COMPLEX IN EXPERIMENTAL CANINE CONGESTIVE-HEART-FAILURE PRODUCED BY RAPID VENTRICULAR PACING
BETA-ADRENERGIC RECEPTOR-G PROTEIN ADENYLATE-CYCLASE COMPLEX IN EXPERIMENTAL CANINE CONGESTIVE-HEART-FAILURE PRODUCED BY RAPID VENTRICULAR PACING
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DOI：
10.1161/01.res.69.6.1546
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发表时间：
1991-12-01
影响因子：
20.1
通讯作者：
MOLINOFF, PB
中科院分区：
文献类型：
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作者：
MARZO, KP;FREY, MJ;MOLINOFF, PB
在慢性快速心室起搏引起的低输出量心力衰竭实验犬模型中，研究了β-肾上腺素能受体-G蛋白-腺苷酸环化酶复合物的变化。暴露于β-肾上腺素能激动剂多巴酚丁胺后发生的收缩反应（测量为左心室峰值+dP/dt）在起搏3周后降低。为了进一步表征对β-肾上腺素能受体刺激的功能反应性降低，使用从对照和起搏动物制备的膜研究β-肾上腺素能受体-腺苷酸环化酶偶联。β-肾上腺素能受体的密度降低了40%，β-1-亚型的选择性下调。受体对拮抗剂放射性配体[I-125]iodocyanopindolol的亲和力保持不变。偶联缺陷表明异丙肾上腺素，氟化物和毛喉素的能力下降，以刺激腺苷酸环化酶从失败的心脏制备的膜。通过免疫印迹和百日咳毒素标记测定G（i-α）（G（i）的α-亚基）的水平显示约30%的适度增加。此外，Mn 2+和纯化的G（S）未能刺激从衰竭心脏制备的膜中的腺苷酸环化酶，表明腺苷酸环化酶本身的催化部分或腺苷酸环化酶与G（S）偶联的能力受损。相比之下，互补测定没有揭示G（s-alpha）（G（s）的α-亚基）的功能活性的差异。总之，这些数据表明，在衰竭的心脏中，肾上腺素能受体的β-1-亚型选择性减少，40 kd G（i）样蛋白增加。在人类特发性扩张型心肌病中也描述了类似的变化。除了这些变化，我们确定了一个可能的缺陷在腺苷酸环化酶的催化亚基的水平。
Changes in the beta-adrenergic receptor-G protein-adenylate cyclase complex were investigated in an experimental canine model of low-output heart failure produced by chronic rapid ventricular pacing. The contractile response occurring after exposure to the beta-adrenergic agonist dobutamine, measured as peak left ventricular +dP/dt, was decreased after 3 weeks of pacing. To further characterize the diminished functional responsiveness to beta-adrenergic receptor stimulation, beta-adrenergic receptor-adenylate cyclase coupling was investigated using membranes prepared from both control and paced animals. The density of beta-adrenergic receptors was decreased by 40% with a selective downregulation of the beta-1-subtype. The affinity of the receptor for the antagonist radioligand [I-125]iodocyanopindolol remained unchanged. A defect in coupling was suggested by a decreased ability of isoproterenol, fluoride, and forskolin to stimulate adenylate cyclase in membranes prepared from failing hearts. Determination of the levels of G(i-alpha) (the alpha-subunit of G(i)) by immunoblotting and pertussis toxin labeling revealed modest increases of approximately 30%. Furthermore, Mn2+ and purified G(s) failed to stimulate adenylate cyclase in membranes prepared from failing hearts, indicating an impairment in the catalytic moiety of adenylate cyclase itself or in the ability of adenylate cyclase to couple to G(s). In contrast, complementation assay did not reveal differences in the functional activity of G(s-alpha) (the alpha-subunit of G(s)). Taken together, these data demonstrate a selective decrease in the beta-1-subtype of adrenergic receptors and an increase in a 40-kd G(i)-like protein in the failing heart. Similar changes have been described in human idiopathic dilated cardiomyopathy. In addition to these changes, we identified a possible defect at the level of the catalytic subunit of adenylate cyclase.