GUANINE-NUCLEOTIDES MODULATE MUSCARINIC RECEPTOR-BINDING IN THE HEART

The binding properties of muscarinic receptors in homogenates of the rat myocardium are altered in the presence of guanine nucleotides. There is a small increase in the affinity constant of the antagonist, [3H]-N-methylscopolamine, and a large decrease in agonist binding. The most potent nucleotide is Gpp(NH)p, with GTP and GDP both being about ten times less active. The effect of GTP on agonist binding is transient whereas that of Gpp(NH)p is more persistent. © 1979 Academic Press, Inc. All rights of reproduction in any form reserved.