Fig. 6.

ATP-induced C11-MDCK cell shrinkage requires transmembrane K⁺ and Na⁺ gradients. A: representative time course of changes in cell volume induced by superfusion with high-K⁺, low-Na⁺ intracellular-like solution (ILS) containing (in mM) 10 NaCl, 110 KCl, 1 MgCl₂, 1 CaCl₂, 5 glucose, and 10 HEPES (pH 7.2, 37°C). B: average volumes of C11-MDCK cells subjected for 60 min to ILS medium or for 30 min to ILS medium followed by 30 min in the same medium containing 50 μM ATP. Initial cell volume measured before application of ILS medium was taken as 100%. Data represent mean values ± SE obtained in 3 independent experiments.