Abstract
HKC-8 cells are a human-derived renal proximal tubular cell line and provide a useful model system for the study of human renal cell function. In this study, we aimed to determine [Ca(2+)](i) signalling mediated by P2 receptor in HKC-8. Fura-2 and a ratio imaging method were employed to measure [Ca(2+)](i) in HKC-8 cells. Our results showed that activation of P2Y receptors by ATP induced a rise in [Ca(2+)](i) that was dependent on an intracellular source of Ca(2+), while prolonged activation of P2Y receptors induced a rise in [Ca(2+)](i) that was dependent on intra- and extracellular sources of Ca(2+). Pharmacological and molecular data in this study suggests that TRPC4 channels mediate Ca(2+) entry in coupling to activation of P2Y in HKC-8 cells. U73221, an inhibitor of PI-PLC, did not inhibit the initial ATP-induced response; whereas D609, an inhibitor of PC-PLC, caused a significant decrease in the initial ATP-induced response, suggesting that P2Y receptors are coupled to PC-PLC. Although P2X were present in HKC-8, The P2X agonist, alpha,beta me-ATP, failed to cause a rise in [Ca(2+)](i). However, PPADS at a concentration of 100 microM inhibits the ATP-induced rise in [Ca(2+)](i). Our results indicate the presence of functional P2Y receptors in HKC-8 cells. ATP-induced [Ca(2+)](i) elevation via P2Y is tightly associated with PC-PLC and TRP channel.
Published Version
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