Lysophosphatidylcholine decreases delayed rectifier K+ current in rabbit coronary smooth muscle cells.
Lysophosphatidylcholine (LPC), which exists abundantly in lipid fraction of oxidized low density lipoprotein, has been implicated in enhanced agonist-induced contraction and increase of intracellular Ca2+. The effect of LPC on the activity of delayed rectifier K+ current (I(dK)), which is a major determinant of membrane potential and vascular tone under resting condition, was examined in rabbit coronary smooth muscle cells using whole cell patch clamping technique. Application of LPC to the bath solution caused a concentration-dependent inhibition of I(dK), and the concentration to produce half-maximal inhibition was 1.51 microM. This effect of LPC on I(dK) was readily reversed after washout of LPC in the bath. The steady-state voltage dependence of I(dK) was shifted to positive direction by both extra- and intracellular application of LPC. Staurosporine (100 nM) pretreatment significantly suppressed the LPC-induced inhibition of I(dK). These results suggest that LPC inhibits I(dK) in rabbit coronary smooth muscle cells by a pathway that involves protein kinase C, and the LPC-induced inhibition of I(dK) may be, at least in part, responsible for the abnormal vascular reactivity in atherosclerotic coronary artery.
Yeon
D
D
Department of Physiology, Yonsei University College of Medicine, Seoul, Korea.
Kwon
S
S
Nam
T
T
Ahn
D
D
D000818:Animals; D003331:Coronary Vessels / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D004336:Drug Antagonism; D004791:Enzyme Inhibitors; D008244:Lysophosphatidylcholines / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000201:enzymology / Q000502:physiology; D018408:Patch-Clamp Techniques; D010455:Peptides / Q000494:pharmacology; D026902:Potassium Channel Blockers; D015221:Potassium Channels / Q000502:physiology; D011493:Protein Kinase C / Q000502:physiology; D011817:Rabbits; D019311:Staurosporine / Q000494:pharmacology
D004791:Enzyme Inhibitors; D008244:Lysophosphatidylcholines; D010455:Peptides; D026902:Potassium Channel Blockers; D015221:Potassium Channels; C064719:iberiotoxin; D011493:Protein Kinase C; D019311:Staurosporine