Ca2+signalling by P2Y receptors in cultured rat aortic smooth muscle cells

Background and purpose: P2Y receptors evoke Ca2+ signals in vascular smooth muscle cells and regulate contraction and proliferation, but the roles of the different P2Y receptor subtypes are incompletely resolved. Experimental approach: Quantitative PCR was used to define expression of mRNA encoding P2Y receptor subtypes in freshly isolated and cultured rat aortic smooth muscle cells (ASMC). Fluorescent indicators in combination with selective ligands were used to measure the changes in cytosolic free [Ca2+] in cultured ASMC evoked by each P2Y receptor subtype. Key results: The mRNA for all rat P2Y receptor subtypes are expressed at various levels in cultured ASMC. Four P2Y receptor subtypes (P2Y1, P2Y2, P2Y4 and P2Y6) evoke Ca2+ signals that require activation of phospholipase C and comprise both release of Ca2+ from stores and Ca2+ entry across the plasma membrane. Conclusions and implications: Combining analysis of P2Y receptor expression with functional analyses using selective agonists and antagonists, we isolated the Ca2+ signals evoked in ASMC by activation of P2Y1, P2Y2, P2Y4 and P2Y6 receptors.