Ontogeny of myocardial adrenoceptors II. Alpha adrenoceptors

Abstract

Extract: The maturation of myocardial alpha adrenoceptors was inves-tigated in dogs. Alpha adrenoceptors were characterized by ra-dioligand binding using [3H]-WB4101. In neonatal cardiac mem-branes, the binding of the ligand was rapid, reversible, of high affinity, saturable and stereoselective. The competition studies with adrenergic agonists and antagonists were indicative of alpha adrenoceptors. In adult dog cardiac membranes, consistent specific binding of the ligand could not be demonstrated. These studies indicate that there is a decrease in alpha adrenergic receptor density of canine cardiac membranes during maturation. Speculation: Changes in membrane receptor density and affinity may be important mechanisms in the ontogeny of myocardial function. © 1982 International Pediatric Research Foundation, Inc.