Serebryakov V N, Zamoiskii V I, Stinnakre J, Tyurmin A, Bregestovski P D
Institute of Experimental Cardiology, Academy of Medical Sciences of the USSR, Moscow.
Biomed Sci. 1990 Jan;1(1):89-94.
The effect of low-density lipoproteins (LDL) on the kinetics of Ca(2+)-dependent K+ channels was investigated in patch-clamp experiments with fetal smooth muscle cells (SMC) from human aorta cultured in normal medium (control SMC), on cells cultured in LDL-free medium for 24-48 h (LDL-SMC), and on cells from the preceding group that had been cultured for a further 24-48 h in a medium containing 50 micrograms ml-1 of LDL (LDL + SMC). Under identical conditions (at 50 mV, in 5 x 10(-7) M [Ca2+]i), the channel kinetics of control SMC and of LDL-SMC were the same, but for LDL + SMC the average time the channels were open (To) was either shorter or longer than in the control cells: To was about 30 ms in control SMC and around either 10 or 50 ms in LDL + SMC. For each group, a plot of log(To) versus membrane potential gave parallel lines, indicating that the voltage dependence remained unchanged. The average time the channels of LDL + SMC were closed (Tc) also bracketed control values. Single-channel conductance was not changed with LDL treatment. Thus LDL-enriched medium induces changes in the kinetics of Ca(2+)-dependent K+ channels. Because cholesterol and its esters carried by LDL can be incorporated into the plasma membrane, the effects seen with LDL may be due to this.
采用膜片钳实验，研究了低密度脂蛋白（LDL）对人主动脉胎儿平滑肌细胞（SMC）中钙依赖性钾通道动力学的影响。这些细胞分别培养于正常培养基中（对照SMC）、无LDL培养基中24 - 48小时（LDL - SMC）以及前一组细胞在含50微克/毫升LDL的培养基中再培养24 - 48小时（LDL + SMC）。在相同条件下（50 mV，细胞内钙离子浓度为5×10⁻⁷ M），对照SMC和LDL - SMC的通道动力学相同，但LDL + SMC通道开放的平均时间（To）比对照细胞短或长：对照SMC中To约为30毫秒，LDL + SMC中To约为10毫秒或50毫秒。对于每组细胞，log(To)与膜电位的关系图呈现平行线，表明电压依赖性保持不变。LDL + SMC通道关闭的平均时间（Tc）也在对照值范围内。单通道电导不受LDL处理的影响。因此，富含LDL的培养基可诱导钙依赖性钾通道动力学发生变化。由于LDL携带的胆固醇及其酯类可掺入质膜，LDL所产生的效应可能归因于此。
