Metabolism of Adrenergic Receptors and Adenylate Cyclase

Abstract

The alpha₁ and beta-adrenergic receptor metabolism was studied at cell confluency in BC₃H₁ and C₆ glioma cells. After their irreversible blockade with phenoxybenzamine and a bromoacetyl derivative of pindolol (Br-AAM-pindolol) respectively the receptor reappearance allows to determine a half life of 23 hours for the alpha₁-adrenergic receptor in BC₃H₁ and a quasi absence of beta-adrenergic receptor metabolism in C₆ glioma cells at confluency. In contrast, beta-adrenergic receptor is rapidly synthesized during cell division. This metabolic stability of beta-adrenergic receptor at confluency was also observed in BC₃H₁ cells using the heavy isotope labeling of the beta-adrenergci receptor (half life of 8 days). This stability was also confirmed by the observation that at confluency in C6 glioma cells, beta adrenergic receptors reappeared at the cell surface after a complete down-regulation. In parallel with the study of the half life of adrenergic receptors, we determined in BC3H1 the halflife of the forskolin stimulated catalytic unit of the adenylate cyclase using heavy isotope tabling method.