The inward rectifier potassium conductance in rat basophilic leukemia cells

Whole-cell recordings were made from rat basophilic leukemia cells. The properties of the cells in the potential range negative to -20 mV could be accounted for by two potassium conductances, a leakage conductance (0.54 +/- 0.01 nS, mean +/- s.e.m., n = 6) and an inward rectifier conductance. The inward rectifier conductance activated at a potential close to EK and had a maximal value of 2.7 +/- 0.22 nS (n = 6). Cesium (2 mM, n = 6) decreased the inward current at every potential. Strontium (10 mM, n = 7) and rubidium (2 mM, n = 3) had a similar effect, but they also increased the slope conductance between -63 and -103 mV. Barium (1-100 microM) blocked selectively the inward rectifying current without affecting the leakage current; the effect was use-, voltage-, and temperature-dependent. TEA decreased the current; the concentration giving 50% inhibition was 37.5 mM. The current was unaffected by phorbol esters as well as several hormones and transmitters that were tested.