title: Binding of A 1,4-dihydropyridine calcium channel activator, (-) S Bay K 8644, to cardiac preparations.
abstract: The 1,4-dihydropyridine Ca2+ channel activator, (-) [3H]Bay K 8644, binds to cardiac membranes and polarized [5 mM K+] and depolarized [50 mM K+] cardiac cells. Binding to microsomal membranes at 25 degrees C indicates a single set of binding sites, KD = 2.9 x 10(-9) M and a site density, 337 fmoles/mg protein, not different from that measured by antagonist 1,4-dihydropyridines. Binding to neonatal rat myocytes at 37 degrees C was independent of membrane potential with a KD value of 5 x 10(-8)M and a site density, 63 fmoles/mg protein, not significantly different from that measured by PN 200 110. These results indicate that 1,4-dihydropyridine activators and antagonists label the same number of binding sites in cardiac tissue, but that activator binding to intact myocytes is voltage-independent.
authors: Department of Biochemical Pharmacology, School of Pharmacy, State University of New York, Buffalo 14260.
authors: J
authors: J
authors: Ferrante
authors: E
authors: E
authors: Luchowski
authors: A
authors: A
authors: Rutledge
authors: D J
authors: DJ
authors: Triggle
mesh_terms: D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn; D015220:Calcium Channels; D002462:Cell Membrane / Q000378:metabolism / Q000502:physiology; D002478:Cells, Cultured; D006168:Guinea Pigs; D006352:Heart Ventricles / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism; D007700:Kinetics; D008297:Male; D008861:Microsomes / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism*; D011869:Radioligand Assay; D051381:Rats; D011978:Receptors, Nicotinic / Q000378:metabolism*; D014316:Tritium
chemical_list: D015220:Calcium Channels; D011978:Receptors, Nicotinic; D014316:Tritium; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester