α 2‐Adrenergic receptor binding in canine Purkinje fibers

FEBS Letters

Lee, Hon-Chi²  Cai, John J.²  Samson, Ricardo A.¹ 

[1] Division of Pediatric Cardiology, Department of Pediatrics, University of Iowa, College of Medicine, Iowa City, IA 52242, USA;Cardiovascular Division, Department of Internal Medicine, University of Iowa, College of Medicine, Iowa City, IA 52242, USA

关键词: Purkinje fibers;    α 2-Adrenergic receptors;    α 1-Adrenergic receptors;    Yohimbine;    Prazosin;    Autoradiography;    Receptor binding;   

DOI  :  10.1016/0014-5793(96)00002-6

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Autoradiograms were developed from free running strands of Purkinje fibers and from left ventricular myocardium of dog hearts exposed to [7-methoxy-³H]prazosin or [O-methyl-³H]yohimbine in the presence or absence of excessive non-radioactive ligands. Both Purkinje fiber and ventricular myocardium showed high density, tissue-specific binding to [³H]prazosin. In contrast, high density, tissue-specific binding to [³H]yohimbine was present in Purkinje fibers but not in ventricular myocardium. Membrane fractions showed high affinity, saturable, and displaceable binding with [³H]yohimbine in preparations from canine cardiac Purkinje fibers but not those from canine cardiac ventricular myocardium. Scatchard analysis of the canine Purkinje membrane α ₂-adrenergic receptor binding showed a B _max of 54.9 fmol/mg protein with a K _d of 6.25 nM. These results confirm the electrophysiological findings that post-junctional α ₂-adrenergic receptors are present in Purkinje fibers.

【 授权许可】

Unknown