The effects of chemical sympathectomy with 6-hydroxydopamine on alpha-adrenoceptor and muscarinic cholinoceptor binding in rat heart ventricle.

The specific binding of 3H-dihydroergocryptine to alpha-adrenoceptors in membranes from the heart ventricle of rats chemically denervated with 6-hydroxydopamine was significantly decreased in comparison with control animals. In contrast the muscarinic cholinoceptor binding of 3H-quinuclinidyl benzilate was unchanged after chemical sympathectomy. These results are interpreted as indicating that the muscarinic receptors are principally postsynaptic but that a significant proportion of the alpha-adrenoceptors are located on noradrenergic nerve terminals.