The role of ATP release in autocrine regulation of cell volume was studied in rat HTC hepatoma cells using whole-cell patch clamp techniques and a Coulter Multisizer. Exposure to hypotonie buffer caused rapid swelling to 1.338±.032 of basal volume followed by regulatory volume decrease (RVD) mediated in part by outwardlyrectified CT currents, ICl-Swell (-1697±121 pA at -80 mV), that showed time-dependent inactivation at depolarizing potentials. The ATP scavenger apyrase (1 U/ml) completely inhibited ICl-Swell and blocked RVD, consistent with a role for extracellular ATP in volume recovery. Hypotonie stress augmented ATP efflux with an increase in ATP conductance 30-fold to 16.5±10.44 pA/pF. Extracellular ATP (2.5-5 μM) but not UTP activated Cl- currents similar to ICl-Swell. Putative P2 receptor blockers suramin (100 nM) and Reactive Blue 2 (10 nM) prevented activation of ICl-Swell and inhibited RVD dosedependently. These observations support an important autocrine role for ATP release and purinergic receptor stimulation in regulation of membrane Cl- permeability and liver cell volume. This work was supported by NIH Grants DK 46082 and DK 43278.
|Original language||English (US)|
|State||Published - Dec 1 1996|
ASJC Scopus subject areas
- Molecular Biology