The protein-specific phosphatase 1 antagonizes the beta-adrenergic increase of the cardiac Ca current.
In isolated ventricular cells from the adult guinea pig heart the slow Ca current was recorded during beta-adrenergic stimulation and during cell dialysis with a protein-specific phosphatase-1 (PPase-1). The increase in the amplitude of ICa during bath application of isoprenaline (5 X 10(-8) M) could be completely reversed by dialysing the cell with 2 microM PPase-1. Lower enzyme concentrations produced smaller effects. The control amplitude of ICa was only little affected by dialysis with PPase-1. The result suggests that PPase-1 is a likely candidate for the downregulation of Ca channels, that Ca channels can open in the dephosphorylated state.
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D006168:Guinea Pigs; D006321:Heart / Q000502:physiology*; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D007545:Isoproterenol / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D009206:Myocardium / Q000166:cytology; D010750:Phosphoproteins / Q000494:pharmacology*; D012269:Ribosomal Proteins
D007473:Ion Channels; D010750:Phosphoproteins; D012269:Ribosomal Proteins; C035690:ribosomal phosphoprotein P1; D007545:Isoproterenol; D002118:Calcium