Studies of solitary semicircular canal hair cells in the adult pigeon. I. Frequency- and time-domain analysis of active and passive membrane properties.
作者信息
Correia M J, Christensen B N, Moore L E, Lang D G
机构信息
Department of Otolaryngology, University of Texas Medical Branch, Galveston 77550.
Hair cells were enzymatically dissociated from the neuroepithelium (cristae ampullares) of the semicircular canals of white king pigeons (Columba livia). Those hair cells determined to be type II by an anatomic criterion, the ratio of the minimum width of the neck to the width of the cuticular plate, were studied with the use of the whole cell patch-clamp technique. 2. The mean +/- SD zero-current membrane potential, Vz, was found to be -54 +/- 12 mV for anterior crista hair cells (n = 71), -62 +/- 14 mV for posterior crista hair cells (n = 14), and -55 +/- 12 mV for lateral (horizontal) crista hair cells (n = 18). The mean +/- SD value of Vz for hair cells from all cristae (n = 103) was -56 +/- 13 mV. 3. Active and passive membrane properties were calculated in the time domain, in voltage- or current-clamp mode, from responses to voltage or current pulses and, in the frequency domain, by fitting a membrane model to admittance magnitude and phase data resulting from current responses to sum-of-sines voltages at different d.c. levels of voltage-clamp membrane potential. 4. The average value +/- SE of input resistance (Rin), over the range from -100 to -60 mV, was found to 1.5 +/- 0.3 G omega from a mean-voltage-as-a-function-of-current plot, V-I, (n = 7) and a mean of 1.4 +/- 0.3 G omega from individual (n = 15) current-as-a-function-of-voltage plots, I-V. A lower mean value 0.8 +/- 0.4 G omega was obtained for the input resistance from frequency-domain calculations for a different set of cells (n = 21). Also, in two different sets of cells, average input capacitance (Cin) was determined to be 12 +/- 3 pF (n = 7) from time-domain estimates and 14 +/- 3 pF (n = 21) from frequency-domain estimates. The (Rin)(Cin) product was 11 ms based on frequency-domain estimates and 17 ms from time-domain estimates. 5. I-V curves for hair cells voltage clamped at -60 mV showed some anomalous rectification for hyperpolarizations between -60 and -120 mV but no detectable N-shape for depolarizations between -50 and 90 mV. The I-V relation showed increasing slope with depolarization through the resting potential (Vz) and increased linearly between -40 and 80 mV; the best-fit straight-line maximum slope conductance for six cells over this range was 17.4 +/- 0.3 nS.(ABSTRACT TRUNCATED AT 400 WORDS)
