Calcium action on the membrane currents possessing the properties of mechano-electric transducer currents in inner hair cells of the Guinea-pig cochlea.
In free-standing hair bundle, depolarization to +80 mV evoked a stable outward current and repolarization to -80 mV evoked a transient inward current attributable to the opening of mechano-electric transducer channels. The study investigated the Ca2+ dependence of this transducer-like membrane current in isolated inner hair cells of guinea-pig cochlea. The amplitude of outward currents increased and the rate of inward current decay, corresponding to adaptation kinetics, decreasing as the extracellular Ca2+ concentrations lessened, whereas the amplitude of outward current decreased and an adaptation accelerated as the extracellular Ca2+ elevated. Treatment with the cAMP agonist, 8-bromo-cAMP, induced an effect similar to that caused by elevating the extracellular Ca2+.
Kimitsuki
Takashi
T
Department of Otorhinolaryngology, Kyushu Central Hospital, Mutual Aid Association of Public School Teachers, Fukuoka, Japan. kimitaka@gent.med.kyushu-u.ac.jp
Matsuda
Keiji
K
Komune
Shizuo
S
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D003051:Cochlea / Q000187:drug effects / Q000378:metabolism*; D000242:Cyclic AMP / Q000037:antagonists & inhibitors / Q000378:metabolism; D045604:Extracellular Fluid / Q000187:drug effects / Q000378:metabolism; D006168:Guinea Pigs; D006199:Hair Cells, Auditory, Inner / Q000187:drug effects / Q000378:metabolism*; D006309:Hearing / Q000187:drug effects / Q000502:physiology; D040542:Mechanotransduction, Cellular / Q000187:drug effects / Q000502:physiology*; D009924:Organ Culture Techniques; D018408:Patch-Clamp Techniques
D015220:Calcium Channels; D015124:8-Bromo Cyclic Adenosine Monophosphate; D000242:Cyclic AMP; D002118:Calcium