Phosphatase inhibition by calyculin A increases i(f) in canine Purkinje fibers and myocytes.
The actions of the phosphatase inhibitor calyculin A on the pacemaker current i(f) were studied in canine Purkinje fibers and myocytes. Calyculin A increased i(f) in response to hyperpolarizations toward the middle of the i(f) activation curve. A three pulse protocol indicated this increase was due to a positive shift of i(f) activation on the voltage axis. Taken together with our previous results (that kinase inhibition with H7 shifts i(f) activation in the negative direction on the voltage axis (2)), these results suggest that phosphorylation is an important regulator of the voltage dependence of i(f) activation.
Department of Physiology and Biophysics, SUNY at Stony Brook 11794-8661.
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Cohen
D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D004285:Dogs; D004553:Electric Conductivity; D005260:Female; D006321:Heart / Q000187:drug effects / Q000502:physiology*; D007700:Kinetics; D008297:Male; D008387:Marine Toxins; D010080:Oxazoles / Q000494:pharmacology*; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors*; D010766:Phosphorylation; D011690:Purkinje Fibers / Q000187:drug effects / Q000502:physiology*
D008387:Marine Toxins; D010080:Oxazoles; C059041:calyculin A; D010749:Phosphoprotein Phosphatases