VOLTAGE-DEPENDENT CA2-HAMSTER OVARY (CHO) CELLS( CHANNELS IN CHINESE)

Voltage-dependent Ca2+ channels were identified in CHO-K1 cells, curre ntly used in molecular biology studies. Experimental data obtained at both macroscopic and single-channel levels using the patch-clamp techn ique show that the Ca2+ current in CHO cells is similar to the high-th reshold L-type of Ca2+ current previously observed in excitable cells. It can be carried by Ca2+ or Ba2+ ions, blocked by both inorganic (Co 2+) and organic (nifedipine, isradipine) Ca2+ channel blockers. The un itary Ca2+ channel activity was characterized by a conductance of 19 p S in 60 mM Ca2+, by single exponential distribution of open times (t = 0.84 ms) and biexponential distribution of closed times (t(f) = 1.67 ms, t(s) = 7.9 ms). However, the functional role of these Ca2+ channel s in CHO cells remains unclear.