AJP - Heart and Circulatory Physiology, Vol 272, Issue 1 17-H24, Copyright © 1997 by American Physiological Society

ARTICLES

Lysophosphatidylcholine transduces Ca2+ signaling via the platelet-activating factor receptor in macrophages

T. Ogita, Y. Tanaka, T. Nakaoka, R. Matsuoka, Y. Kira, M. Nakamura, T. Shimizu and T. Fujita
Fourth Department of Internal Medicine, Faculty of Medicine, University of Tokyo, Japan.

To clarify the molecular mechanism underlying the lysophosphatidylcholine (LPC) signaling, we studied the effect of LPC on the intracellular free calcium concentration ([Ca2+]i) in murine peritoneal macrophages. LPC when added alone induced biphasic elevation of [Ca2+]i, which consisted of a rapid increase followed by sustained elevation. LPC, when added with equimolar cholesterol, induced only the rapid increase in [Ca2+]i, which was blocked by WEB-2086, a selective platelet-activating factor (PAF) receptor antagonist. These results suggest LPC exerts a specific Ca2+ signaling. The sustained elevation reflected the cell lysis. Furthermore, we confirmed its pathway in a more specific manner using cloned PAF receptors expressed in Chinese hamster ovary cells. LPC induced an elevation of [Ca2+]i in a concentration-dependent manner only when the PAF receptor had been expressed, and the elevation of [Ca2+]i was blocked by WEB-2086. Taken together, LPC transduces Ca2+ signaling via the PAF receptor. Activation of the PAF receptor by LPC may indicate its novel important role in the pathogenesis of atherosclerosis.

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