Characterization of outward potassium current in embryonic chick heart cells.
OBJECTIVE
To characterize a voltage-dependent outward K+ current in cultured heart cells of 14-16-day-old embryos of yellow chick.


METHODS
The patchclamp technique in the whole-cell configuration was used.


RESULTS
The kinetics and the pharmacology of the outward K+ current in our cell mold were different from those described in white chick. Like the calcium-activated K+ current, blocker of calcium channel, CdCl2, eliminated the current of more than 95%. Isoproterenol provoked an increase of peak amplitude (137% +/- 47%, n = 16 cells) and acceleration of activation kinetics in the outward K+ current (the time reaching a peak current reduced from 36 ms +/- 10 ms to 16 ms +/- 9 ms). This effect of isoproterenol was mimiced by cAMP. In addition, a frequency-dependent decrease in peak amplitude of the current occurred after cAMP-induced phosphorylation.


CONCLUSIONS
There are species- and/or cell-type-specific difference in the K+ channels properties. In embryonic yellow chick heart cells, the phospholation of channel could not only modulate the activation kinetic properties of the calcium-activated potassium channel, but also change their recovery kinetics.
Mei
Y A
YA
Department of Physiology and Biophysics, Liren Laboratory, Fudan University, Shanghai, China. yamei@fudan.edu.cn
Huang
L X
LX
Wei
H
H
Sun
J T
JT
Zhou
H Q
HQ
Zhang
Z H
ZH
D000818:Animals; D019256:Cadmium Chloride / Q000494:pharmacology*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002478:Cells, Cultured; D002642:Chick Embryo; D000242:Cyclic AMP / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology*; D009206:Myocardium / Q000166:cytology*; D018408:Patch-Clamp Techniques; D010766:Phosphorylation; D015221:Potassium Channels / Q000187:drug effects*
D002121:Calcium Channel Blockers; D015221:Potassium Channels; D000242:Cyclic AMP; D019256:Cadmium Chloride; D007545:Isoproterenol