Dihydrostreptomycin modifies adaptation and blocks the mechano-electric transducer in chick cochlear hair cells.
Block of the mechano-electric transduction (MET) channel by dihydrostreptomycin (DHSM) and its effects on adaptation were investigated in dissociated cochlear hair cells of the chick with a whole-cell patch-electrode voltage clamp technique. DHSM reversibly blocked the MET channel in a dose- and voltage-dependent manner. At -50 mV, DHSM blocked the MET channel with a Hill coefficient of approximately 1 and a dissociation constant (Kd) of 2 x 10(-5) M. Rate constants for the DHSM to bind and to unbind to and from the channel were estimated, and could be larger than 5 x 10(7) M-1.s-1 and 1 x 10(3) s-1, respectively. The amplitude of MET current decreased during a constant displacement of the hair bundle. This current decay, the adaptation, disappeared in the DHSM medium. The disappearance and the emergence of adaptation did not have a simple relationship with the block of MET channel by DHSM, but appeared with some delay.
Kimitsuki
T
T
National Institute for Physiology Sciences, Okazaki, Japan.
Ohmori
H
H
D000222:Adaptation, Physiological / Q000187:drug effects*; D000818:Animals; D000831:Animals, Newborn; D002645:Chickens; D004096:Dihydrostreptomycin Sulfate / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D006198:Hair Cells, Auditory / Q000187:drug effects* / Q000502:physiology; D007473:Ion Channels / Q000037:antagonists & inhibitors / Q000187:drug effects; D007700:Kinetics; D009431:Neural Conduction / Q000187:drug effects
D007473:Ion Channels; D004096:Dihydrostreptomycin Sulfate