Dihydrostreptomycin goes through the mechano-electric transduction channel in chick cochlear hair cells.
OBJECTIVE
This study evaluated the ability of dihydrostreptomycin (DHSM) to go through the mechano-electric transduction (MET) channels in hair cells under physiological conditions.


METHODS
Tall hair cells were isolated from the chick basilar membrane (cochlea). Mechanical stimulation was applied by a glass rod attached to a piezoelectric bimorph, and MET currents were recorded with a whole-cell patch technique. The voltage-dependent block of DHSM to MET channel was estimated by calculating the relative conductances (the ratio of MET current in DHSM saline to DHSM-free saline) at various membrane potentials.


CONCLUSIONS
At membrane potentials between -100 and +50 mV, DHSM behaves as a voltage-dependent blocker according to a partial block model. At membrane potentials more negative than -100 mV, however, DHSM blocking decreased. This finding differed from the partial block model, but indicated that DHSM escaped through the channel pore into the cytoplasm by acting as a permeant channel blocker due to the large electrical driving force.
Kimitsuki
Takashi
T
Department of Otolaryngology, Graduate School of Medical Sciences, Faculty of Medicine, Kyushu University, Fukuoka 812-8582, Japan. kimitaka@qent.med.kyushu-u.ac.jp
Wakasaki
Takahiro
T
Nawate
Ayako
A
Komune
Noritaka
N
Takaiwa
Kazutaka
K
Ohashi
Mitsuru
M
Komune
Shizuo
S
D000818:Animals; D000900:Anti-Bacterial Agents / Q000493:pharmacokinetics*; D002645:Chickens; D003593:Cytoplasm / Q000378:metabolism; D004096:Dihydrostreptomycin Sulfate / Q000493:pharmacokinetics*; D006198:Hair Cells, Auditory / Q000187:drug effects* / Q000502:physiology; D066298:In Vitro Techniques; D015640:Ion Channel Gating / Q000187:drug effects*; D007473:Ion Channels / Q000037:antagonists & inhibitors* / Q000502:physiology; D040542:Mechanotransduction, Cellular / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008954:Models, Biological; D018408:Patch-Clamp Techniques
D000900:Anti-Bacterial Agents; D007473:Ion Channels; D004096:Dihydrostreptomycin Sulfate