Elevation of intracellular calcium induced by the intrapipette perfusion technique modifies membrane ion currents in the chick cochlear hair cell

The concentration of intracellular calcium ion ([Ca²⁺](i)) was altered in the same hair cell dissociated from a chick cochlea by the intrapipette perfusion technique. At a membrane potential of -40 mV, the elevation of [Ca²⁺](i) generated outward-going currents within 60 sec when the intrapipette solution was based on KCl. In controls, at membrane potentials more positive than -50 mV, outward K⁺ currents were observed and at large positive potentials, the outward K⁺ current decreased, showing an N-shaped I-V relationship. This outward K⁺ current was increased by elevation of [Ca²⁺](i) and was partially suppressed by a TEA-containing extracellular solution. We suggest that the Ca²⁺ increased by the intrapipette perfusion technique operates directly inside the cell membrane and activates Ca²⁺- activated K⁺ currents.