Two classes of potassium currents in Xenopus muscle cells in young cultures

The aim of the present study was to determine if both inactivating and non-inactivating potassium currents occur in skeletal muscle cells at early times in culture. Whole cell current was recorded from embryonic muscle cells within 4-10 h of plating. We found that in the cells which had an outward current, half had a current that did not inactivate and half had a current that inactivated during a maintained depolarization (100 ms). The two groups of cells did not differ in their age in culture or resting membrane potential. The results indicate that Xenopus skeletal muscle cells can acquire both types of outward potassium current early in culture life.