[Calcium channels in bullfrog saccular hair cells].
In order to understand the cochlear physiology at a cellular and molecular level, Ca2+ channels were studied in cell-attached recordings from the basolateral membrane of the bullforg saccular hair cells with the EPC-9 patch-clamp system. Pipettes contained 110 mM Ba2+ and the membrane potential was zeroed with isotonic potassium aspartate. Data acquisition and analysis were performed using E9SCREEN and M2LAB software. L-type channel was distinguished by a single-channel conductance of 26 pS, activation range between -10 and +40 mV and intense activity even at a holding potential of -40 mV. The L-type channel showed characteristic bursts of brief openings (mode 1) interrupted occasionally by longer openings (mode 2). Bay K 8644 promoted the mode 2 activity and nifedipine inhibited L-type channel activity. Another type of calcium channels, 20 pS channel, was detected by -50 to +10 mV depolarizing steps from a holding potential of -40 mV or -80 mV. This channel was insensitive to dihydropyridines and resembled the N-type channel.
Su
Z
Z
Institute of Otolaryngology, PLA General Hospital, Beijing.
Jiang
S
S
Gu
R
R
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000818:Animals; D015220:Calcium Channels / Q000187:drug effects*; D004095:Dihydropyridines / Q000494:pharmacology; D018069:Hair Cells, Vestibular / Q000378:metabolism / Q000502:physiology*; D008564:Membrane Potentials; D009543:Nifedipine / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D011892:Rana catesbeiana
D015220:Calcium Channels; D004095:Dihydropyridines; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D009543:Nifedipine