Single-Channel L-Type Ca2+ Currents in Chicken Embryo Semicircular Canal Type I and Type II Hair Cells

Few data are available concerning single Ca channel properties in inner ear hair cells and particularly none in vestibular type I hair cells. By using the cell-attached configuration of the patch-clamp technique in combination with the semicircular canal crista slice preparation, we determined the elementary properties of voltage-dependent Ca channels in chicken embryo type I and type II hair cells. The pipette solutions included Bay K 8644. With 70 mM Ba2+ in the patch pipette, Ca channel activity appeared as very brief openings at −60 mV. Ca channel properties were found to be similar in type I and type II hair cells; therefore data were pooled. The mean inward current amplitude was −1.3 ± 0.1 (SD) pA at − 30 mV (n = 16). The average slope conductance was 21 pS (n = 20). With 5 mM Ba2+ in the patch pipette, very brief openings were already detectable at −80 mV. The mean inward current amplitude was −0.7 ± 0.2 pA at −40 mV (n = 9). The average slope conductance was 11 pS (n = 9). The mean open time and t...