title: Nitrendipine and isoproterenol induce phosphorylation of a 42,000 dalton protein that co-migrates with the affinity labeled calcium channel regulatory subunit.
abstract: Slow inward calcium channels in canine cardiac membranes were affinity labeled with the calcium channel analogue, [3H]o-NCS [2,6 dimethyl-3,5-dicarbomethoxy-4-(2- isothiocyanatophenyl )-1, 4-dihydropyridine], in the presence and absence of cold o-NCS or nicardipine. A major specifically labeled peak was identified with Mr 42,000 on NaDodSO4 polyacrylamide gels. In parallel experiments the effects of the calcium channel antagonist, nitrendipine and a variety of other chemical mediators were tested for their ability to stimulate protein phosphorylation in cardiac membranes. These data demonstrate that both nitrendipine and isoproterenol induce the phosphorylation of a 42,000 dalton protein via a kinase endogenous to the cardiac membranes and that the effects of isoproterenol are attenuated by carbachol.
mesh_terms: D000345:Affinity Labels; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D004285:Dogs; D004591:Electrophoresis, Polyacrylamide Gel; D066298:In Vitro Techniques; D007473:Ion Channels / Q000378:metabolism*; D007545:Isoproterenol / Q000494:pharmacology*; D008565:Membrane Proteins / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism; D009543:Nifedipine / Q000031:analogs & derivatives* / Q000494:pharmacology; D009568:Nitrendipine; D010766:Phosphorylation
chemical_list: D000345:Affinity Labels; D007473:Ion Channels; D008565:Membrane Proteins; D009568:Nitrendipine; D009543:Nifedipine; D007545:Isoproterenol