Characterization of outward potassium current in embryonic chick heart cells

• Published in: Zhōngguó yàolĭ xuébào Vol. 20; no. 4; pp. 303 - 307
• Main Authors: Mei, Y A, Huang, L X, Wei, H, Sun, J T, Zhou, H Q, Zhang, Z H
• Format: Journal Article
• Language: English
• Published: China 01.04.1999
• Subjects: Animals; Cadmium Chloride - pharmacology; Calcium Channel Blockers - pharmacology; Cells, Cultured; Chick Embryo; Cyclic AMP - pharmacology; Isoproterenol - pharmacology; Myocardium - cytology; Patch-Clamp Techniques; Phosphorylation; Potassium Channels - drug effects
• ISSN: 0253-9756

To characterize a voltage-dependent outward K+ current in cultured heart cells of 14-16-day-old embryos of yellow chick. The patchclamp technique in the whole-cell configuration was used. 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. 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.