Two types of calcium channels in bullfrog saccular hair cells

Hear Res. 1995 Jul;87(1-2):62-8. doi: 10.1016/0378-5955(95)00079-j.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / pharmacology
  • Animals
  • Aspartic Acid / chemistry
  • Calcium Channel Agonists / pharmacology
  • Calcium Channels / analysis*
  • Calcium Channels / physiology
  • Hair Cells, Auditory / chemistry*
  • Hair Cells, Auditory / cytology
  • Kinetics
  • Patch-Clamp Techniques
  • Rana catesbeiana
  • Saccule and Utricle / chemistry*

Substances

  • Calcium Channel Agonists
  • Calcium Channels
  • Aspartic Acid
  • 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester