ABSTRACT
The ß-adrenergic receptor complex (ßAR), has been studied in hypoxic myocardium, but incompletely evaluated in hypothermia. There is no difference in ßAR receptor density or affinity between H and C animals. In contrast the tightness of coupling of the ßAR to the GTP binding protein, as indicated by the relative distribution of high and low affinity receptors for the agonist isoproterenol, whether determined alone or in the presence of Gpp(NH)p, is clearly increased in H over C animals. In the period of preparation for hibernation, a number of known biochemical transformations occur in the composition and structure of the plasma membrane. Survival of the animal at low tissue temperatures may be facilitated by biochemical changes. Characteristics of the ßAR determined in the animal aroused from hibernation were identical to those found in the summer animal. The absence of a hibernation-associated difference in the cycreconstitution assay suggests no change in the intrinsic activity of the stimulatory guanine nucleotide binding protein Gs.
