Two types of calcium channels in bullfrog saccular hair cells.
Ca2+ channels were studied in cell-attached recordings from the basolateral membrane of the bullfrog 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 or -80 mV. This channel was insensitive to dihydropyridines and resembled the N-type channel.
Su
Z L
ZL
Institute of Otolaryngology, Chinese PLA General Hospital, Beijing, People's Republic of China.
Jiang
S C
SC
Gu
R
R
Yang
W P
WP
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000818:Animals; D001224:Aspartic Acid / Q000737:chemistry; D002120:Calcium Channel Agonists / Q000494:pharmacology; D015220:Calcium Channels / Q000032:analysis* / Q000502:physiology; D006198:Hair Cells, Auditory / Q000737:chemistry* / Q000166:cytology; D007700:Kinetics; D018408:Patch-Clamp Techniques; D011892:Rana catesbeiana; D012444:Saccule and Utricle / Q000737:chemistry*
D002120:Calcium Channel Agonists; D015220:Calcium Channels; D001224:Aspartic Acid; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester