Cell potential of isolated outer hair cells as a function of extracellular K+ concentration

Outer hair cells were isolated from apical turns of the guinea pig cochlea. The membrane potential differences of cells in extracellular medium with 5.8, 14.0, 28.9 or 67.5 mmol/l of potassium were -72.0 +/- 0.6 (mean +/- SEM, n = 93), -50.1 +/- 2.1 (n = 4), -37.7 +/- 0.5 (n = 73) or -20.0 +/- 1.5 mV (n = 16), respectively. Membrane depolarization can explain two thirds of the K(+)-induced shortening of isolated outer hair cells.