Lysophosphatidic acid induces inward currents in Xenopuslaevis oocytes; evidence for an extracellular site of action

Abstract Lysophosphatidic acid (LPA) is a naturally occurring phospholipid that can elicit platelet aggregation, smooth muscle contraction and, in fibroblasts, cell proliferation. We now report that LPA in nanomolar concentrations evokes an inward current in native , defolliculated Xenopus laevis oocytes. Extracellular application of LPA from a pressuer pipette to the surface of the oocyte induced an immediate response. In contrast, intracellular injection of the same amount of LPA failed to elicit a response. These data suggest the existence of a Ca 2+ -mobilizing, endogeneous LPA receptor in the Xenopus laevis oocyte cell membrane.