Effect of cyclopiazonic acid on membrane currents in isolated inner hair cells from guinea-pig cochlea.
Cyclopiazonic acid (CPA) is a reticulum-like intracellular Ca(2+) store depletory, which raises intracellular Ca(2+) concentration. The effect of CPA on membrane currents in isolated inner hair cells (IHCs) from guinea-pig cochlea was investigated by the patch-clamp technique in the whole-cell configuration. Four out of eight IHCs showed an augmentation of the currents and the other four cells showed an inhibition of the currents by extracellular CPA application. The activation kinetics of outward currents were not changed by CPA. Three out of four IHCs obtained from the basal part of the cochlea demonstrated augmentation, whereas three out of four IHCs from the apical part demonstrated inhibition of the currents. This result suggests that Ca(2+)-activated currents were dominant in the basal IHCs of the cochlea.
Kimitsuki
Takashi
T
Department of Otorhinolaryngology, Miyazaki Medical College, 5200 Kihara, Kiyotake-cho, Miyazaki 889-1692, Japan. kimituki@fc.miyazaki-med.ac.jp
Nakashima
Takahiro
T
Wada
Yuko
Y
Ohashi
Mitsuru
M
Komune
Shizuo
S
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism*; D004558:Electric Stimulation; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006168:Guinea Pigs; D006199:Hair Cells, Auditory, Inner / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D006309:Hearing / Q000502:physiology; D007211:Indoles / Q000494:pharmacology*; D007424:Intracellular Fluid / Q000187:drug effects / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D024681:Potassium Channels, Calcium-Activated / Q000187:drug effects / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology
D004791:Enzyme Inhibitors; D007211:Indoles; D024681:Potassium Channels, Calcium-Activated; D000252:Calcium-Transporting ATPases; D002118:Calcium; C000543:cyclopiazonic acid