Effect of low-density lipoproteins on Ca(2+)-dependent K+ channels in the membrane of smooth muscle cells isolated from human fetal aorta.
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.
Serebryakov
V N
VN
Institute of Experimental Cardiology, Academy of Medical Sciences of the USSR, Moscow.
Zamoiskii
V I
VI
Printseva OYu
Stinnakre
J
J
Tyurmin
A
A
Bregestovski
P D
PD
D001011:Aorta / Q000166:cytology / Q000196:embryology; D002118:Calcium / Q000494:pharmacology*; D002478:Cells, Cultured; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects; D008077:Lipoproteins, LDL / Q000494:pharmacology*; D008564:Membrane Potentials; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000196:embryology / Q000378:metabolism; D015221:Potassium Channels / Q000187:drug effects*
D008077:Lipoproteins, LDL; D015221:Potassium Channels; D002118:Calcium