Lysophosphatidylcholine alters vascular tone in rat aorta by suppressing endothelial [Ca(2+)](I) signaling.
The detailed mechanism of how lysophosphatidylcholine (LPC) suppresses endothelium-dependent vasodilatation is unclear at present. We investigated the effects of LPC on endothelial intracellular calcium (EC [Ca(2+)](i)) signaling and vascular tone simultaneously using a new technique we developed. Fura-2-labeled rat aortic specimens were mounted in a tissue flow chamber and precontracted with phenylephrine (5 x 10(-8) M). Under either basal or agonist-stimulated conditions, the EC [Ca(2+)](i) level was calculated from fura 2 fluorescence ratio images, and the vascular tone was estimated by measuring the relative displacement of the fluorescence images. Although both acetylcholine (ACh)-induced EC [Ca(2+)](i) elevation and the concomitant vasorelaxation were partially suppressed in specimens pretreated with LPC (20 microM), the quantitative relationship between EC [Ca(2+)](i) elevation and the corresponding vasorelaxation was unaffected. A high concentration of LPC (40 microM) completely eliminated ACh-evoked [Ca(2+)](i) elevation and vasodilatation. It has been reported that exposing vascular tissue to a calcium-free buffer causes a reduction in the EC [Ca(2+)](i) level and the accompanying vasoconstriction. Pretreatment with 20 microM LPC reduced the basal EC [Ca(2+)](i) level and abolished the calcium-free solution-induced EC [Ca(2+)](i) reduction and vasoconstriction. We conclude that LPC impairs endothelium-dependent vasorelaxation mainly by reducing the basal EC [Ca(2+)](i) level and suppressing agonist-evoked EC [Ca(2+)](i) signaling.
Huang
Tung-Yi
TY
Department of Physiology and Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan, ROC.
Chen
Hsiun-Ing
HI
Liu
Chin-Yen
CY
Jen
Chauying J
CJ
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001011:Aorta / Q000187:drug effects* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000502:physiology*; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism; D005456:Fluorescent Dyes / Q000378:metabolism; D016257:Fura-2 / Q000378:metabolism; D066298:In Vitro Techniques; D008244:Lysophosphatidylcholines / Q000494:pharmacology*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology*; D014665:Vasodilator Agents / Q000494:pharmacology
D005456:Fluorescent Dyes; D008244:Lysophosphatidylcholines; D014665:Vasodilator Agents; D000109:Acetylcholine; D002118:Calcium; D016257:Fura-2