Nucleotide receptors activate cation, potassium, and chloride currents in a liver cell line

摘要: By use of whole cell patch-clamp techniques, the effects extracellular ATP on membrane ion currents HTC cells from a rat liver tumor line were evaluated. (500 microM) or nonhydrolyzable analogue adenosine 5'-O-(3-thiotriphosphate) caused sequential activation three currents: Icat (-1,325 +/- 255 pA at -80 mV) occurred early, was due to increased Na+ and K+ permeability, present in 56% 64 consecutive cells, rapidly inactivated; IK (274 45 0 59% also ICl (1,172 237 +60 94% studies, sustained, exhibited outward rectification current-voltage relation. All 39% cells. Increasing intracellular Ca2+ concentration ([Ca2+]i) by exposure 5'-nucleotide receptor agonist UTP thapsigargin activated but not ICl, whereas increasing ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid pipette (> = 5 mM) inhibited ATP-dependent ICl. A P2x-preferring alpha, beta-methylene did activate currents; P2y-preferring 2-methylthioadenosine triphosphate concentrations 500 microM 50 microM. In perforated patch recordings, produced triphasic changes potential with initial depolarization Icat, subsequent hyperpolarization IK, later sustained These findings indicate that modulates permeability through mediated receptors which mobilize [Ca2+], separate Ca(2+)-independent mechanism.