Effects of adrenalectomy on binding to and actions of adrenergic receptors.
Adrenalectomy results in significant changes in the mechanism of adrenergic activation of hepatic glycogenolysis. In adrenalectomized rats a greater role for the beta-adrenergic receptor is observed, whereas the alpha 1-adrenergic-mediated phosphorylase activation declines. Our present findings document that adrenalectomy causes a significant decrease in the high-affinity population of the alpha 1-adrenergic receptor labelled with [3H]adrenaline. Our data indicate a large increase in the number of beta-adrenergic binding sites after adrenalectomy. This increase was not consistent with the observed modest increase in the beta-adrenergic-mediated activation of cyclic AMP accumulation and glycogen phosphorylase. When alpha-adrenergic antagonists are present along with the catecholamine, a 100% increase in the adrenaline-mediated accumulation of cyclic AMP in hepatocytes from adrenalectomized rats was observed. Adrenalectomy was also shown to cause a significant increase in the hepatic alpha 2-adrenergic binding sites. These data are consistent with an inhibitory role on the beta-adrenergic-mediated activation of glycogenolysis by the hepatic alpha 2-adrenergic receptor in adrenalectomy.
D000315:Adrenalectomy; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D004837:Epinephrine / Q000378:metabolism; D066298:In Vitro Techniques; D008099:Liver / Q000378:metabolism*; D008297:Male; D006005:Phosphorylases / Q000378:metabolism; D011433:Propranolol / Q000494:pharmacology; D011869:Radioligand Assay; D051381:Rats; D011919:Rats, Inbred Strains; D011941:Receptors, Adrenergic / Q000187:drug effects / Q000378:metabolism*; D015016:Yohimbine / Q000494:pharmacology
D011941:Receptors, Adrenergic; D015016:Yohimbine; D011433:Propranolol; D000242:Cyclic AMP; D006005:Phosphorylases; D004837:Epinephrine