ENDOTHELIN-INDUCED CALCIUM SIGNALING IN CULTURED MOUSE MICROGLIAL CELLS IS MEDIATED THROUGH ETB RECEPTORS

MICROGLIAL cells are the intrinsic immunocompetent cells of the centra l nervous system, which are activated by brain tissue damage. In this paper Ne investigated the ability of endothelins (ETs), which are pote nt vasoconstrictors, to induce intracellular calcium signals in cultur ed microglia cells. Both endotheIin-1 and endothelin-3 increased intra cellular Ca2+ concentration ([Ca2+](i)). These [Ca2+](i) transients we re mimicked by BQ3020, an ETB receptor agonist and blocked by BQ788, a selective ETB antagonist, respectively. The calcium signals induced b y the endothelins persisted in Ca2+-free media. Transcripts encoding t he ETB receptor were detected in purified microglial cultures and cDNA fragments derived from ETB receptor mRNA were amplified from 9% of el ectrophysiologically characterized microglial cells by the use of sing le-cell RT-PCR.