Voltage-dependent Ca2+ channels in Chinese hamster ovary (CHO) cells

Voltage-dependent Ca2+ channels were identified in CHO-K1 cells, currently used in molecular biology studies. Experimental data obtained at both macroscopic and single-channel levels using the patch-clamp technique show that the Ca2+ current in CHO cells is similar to the high-threshold L-type of Ca2+ current previously observed in excitable cells. It can be carried by Ca2+ or Ba2+ ions, blocked by both inorganic (Co2+) and organic (nifedipine, isradipine) Ca2+ channel blockers. The unitary Ca2+ channel activity was characterized by a conductance of 19 pS in 60 mM Ca2+, by single exponential distribution of open times (t = 0.84 ms) and biexponential distribution of closed times (tf = 1.67 ms, ts = 7.9 ms). However, the functional role of these Ca2+ channels in CHO cells remains unclear.