ATP released by hypotonic stimulation regulates cell volume via P_2 purinergic receptor

• Published in: Japanese Journal of Pharmacology 2001, Vol.85 (suppl.1), p.63-63
• Main Authors: Kumiko Kawasaki, Naoko Tanaka, Kazumasa Shinozuka, Yoko Kubota, Hideya Mizuno, Kazuki Nakamura, Michio Hashimoto, Masaru Kunitomo
• Format: Article
• Language: Japanese
• ISSN: 0021-5198

It is well known that swelling of hypotonic cells activates a regulatory volume decrease (RVD). We reported that the ATP released by hypotonicity increased the intracellular Ca^2+ ([Ca^2+ ]i) level of cultured endothelial cells via P_2 , purinergic receptor. In the present study, the role of ATP in the increase in [Ca^2+ ]i level and RVD was investigated. Cell volume and [Ca^2+ ]i were analyzed by a phase contrast microscopic imaging system (NIH-image) and a fluorescent confocal microscopic imaging system (ARGUS 50), respectively. ATP and its metabolites were analyzed by HPLC-fluorescent detection. In rat caudal arterial endothelial cells, hypotonicity increased [Ca^2+ ]i level and overflow of ATP. Hypotonicity-induced increase in the [Ca^2+ ]i level was prevented by PPADS (a P_2 purinoceptor antagonist), U-73122 (a phospholipase C inhibitor) and thapsigargin (a Ca^2+ pump inhibitor). However, the increase in cell volume was potentiated by PPADS, U-73122 and by thapsigargin. It was also noted that 2-methylthio ATP (P, purinoceptor agonist) decreased the cell volume, an action that was blocked by PPADS. From these results, it is suggested that ATP, which is released by hypotonicity, may facilitate RVD via P_2 purinoceptor-induced increase in the [Ca^2+ ]i level.