부산대학교 도서관

Summary Trains of long-duration “action potentials” were induced by Ba2+ in osteoblast-like rat osteosarcoma cells (ROS 17/2.8), under current clamp and voltage clamp. Large depolarizing pulses were seen in microelectrode measurements at 37°C following the addition of 10 or 20mm Ba2+ to physiological bathing medium. Application of BAY K 8644 resulted in the onset of the pulses at earlier times and at more negative potentials. The pulses were blocked by nifedipine and Cd2+, but not by Ni2+. Large inward current pulses were seen in whole-cell patch technique voltage-clamp measurements at 37°C in the presence of from 10 to 110mm Ba2+ in the bathing medium. The current pulses were not seen at 22°C in the presence of 110mm Ba2+, but could be induced by BAY K 8644. These pulses were not blocked by TTX, but were blocked by nifedipine, Cd2+, Zn2+, Co2+, and by an increase in bathing [Ca2+]. The shape and frequency of the current pulses were the same as for voltage pulses under current clamp.