The Effect of Cold Cardioplegic Cardiac Arrest and Electrically Induced Ventricular Fibrillation on Human Cardiac β-Adrenoceptors During Open-Heart Surgery

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I]iodocyanopindolol binding before CPB, defined as the "control," immediately after initiation, defined as "before," and immediately before the cessation of CCCA or EIVF, defined as "after." The density of βARs was equivalent between the "control" and "before" groups; however, during CPB with EIVF, the density of βARs decreased significantly (P < 0.001), whereas during CPB with CCCA, it increased significantly (P < 0.01). The rate of changes of the βAR density was not correlated with the "before"–"after" interval, and the affinity of the βARs did not change throughout these CPBs. These findings demonstrate that: CPB alone does not affect cardiac βARs, at least until the onset of EIVF or CCCA; CPB with EIVF induces rapid desensitization of cardiac βARs; and CPB with CCCA induces rapid sensitization of cardiac βARs.