The catalytic subunit of cyclic AMP-dependent protein kinase directly inhibits sodium channel activities in guinea-pig ventricular myocytes.
We investigated the effects of the purified catalytic subunit (C subunit) of the cAMP-dependent protein kinase (A-kinase) on the cardiac Na+ channel currents. Single Na+ channel currents in guinea-pig ventricular myocytes were recorded using the patch clamp technique of the inside-out configuration. Application of C subunit decreased the peak average current and slowed the current decay, effects which were caused by decrease in the open probability of Na+ channels and increase in the first latency, whereas the unitary current amplitude and mean open times were not affected. We conclude that the cardiac Na+ channel is directly modulated by phosphorylation process through A-kinase.
Sunami
A
A
Department of Cardiovascular Diseases, Tokyo Medical and Dental University, Japan.
Fan
Z
Z
Nakamura
F
F
Naka
M
M
Tanaka
T
T
Sawanobori
T
T
Hiraoka
M
M
D000818:Animals; D002384:Catalysis; D006168:Guinea Pigs; D006352:Heart Ventricles; D015640:Ion Channel Gating / Q000187:drug effects; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D011494:Protein Kinases / Q000737:chemistry / Q000494:pharmacology; D015222:Sodium Channels / Q000187:drug effects*
D015222:Sodium Channels; D011494:Protein Kinases