Albitz R, Droogmans G, Nilius B, Casteels R
Medical Academy Erfurt, Germany.
Cell Calcium. 1992 Apr;13(4):203-10. doi: 10.1016/0143-4160(92)90008-g.
The action of the blood clotting enzyme thrombin on single channel and whole cell Ca(2+)-currents was studied in isolated mammalian cardiac myocytes. Thrombin, at a concentration of 10(-8) mol/l, increased the Ca(2+)-channel activity in cell-attached patches. The mean open probability of the channel was enhanced, while the number of sweeps without openings, which reflects the availability of the channel, was significantly reduced. Neither the single channel conductance nor the activation curve were affected by thrombin. Thrombin was added to the bath solution, and its effect is therefore indirect and probably mediated via a second messenger. However, thrombin did not affect whole-cell Ca(2+)-currents, whereas a beta-adrenergic stimulation in the same cell increased the Ca(2+)-current. It is concluded that thrombin affects an intracellular mechanism for Ca2+ channel current regulation, which is still unknown and which is rapidly lost during conventional whole-cell Ca2+ current measurements.
在分离的哺乳动物心肌细胞中研究了凝血酶对单通道和全细胞钙电流的作用。浓度为10^(-8)摩尔/升的凝血酶增加了细胞贴附式膜片中的钙通道活性。通道的平均开放概率增强，而反映通道可用性的无开放扫描次数显著减少。凝血酶既不影响单通道电导，也不影响激活曲线。凝血酶添加到浴液中，因此其作用是间接的，可能通过第二信使介导。然而，凝血酶不影响全细胞钙电流，而同一细胞中的β-肾上腺素能刺激增加了钙电流。得出的结论是，凝血酶影响一种细胞内钙通道电流调节机制，该机制仍然未知，并且在传统的全细胞钙电流测量过程中会迅速丧失。
