Pflügers Archiv

, Volume 409, Issue 6, pp 607–615

Calcium and ATP regulate the activity of a non-selective cation channel in a rat insulinoma cell line

  • N. C. Sturgess
  • C. N. Hales
  • M. L. J. Ashford
Transport Processes, Metabolism and Endocrinology; Kidney, Gastrointestinal Tract, and Exocrine Glands

DOI: 10.1007/BF00584661

Cite this article as:
Sturgess, N.C., Hales, C.N. & Ashford, M.L.J. Pflugers Arch. (1987) 409: 607. doi:10.1007/BF00584661

Abstract

A calcium-acivated non-selective cation channel was observed in isolated plasma membrane patches from an insulin-secreting cell line (CRI-Gl). The conductance of the channel was approximately 25 pS with identical (140 mM KCl) solutions on either side of the membrane. However, some rectification was observed (smaller outward current) when sodium ions were present extracellularly. The channel was inactive on exposure to an intracellular calcium concentration of 10−6 M and required high (greater than 10−4 M) concentrations for a significant degree of activation. The open-state probability of the channel was voltage dependent, increasing with membrane depolarization. Analysis of single channel kinetics indicated that there were at least two open and two closed states. Application of ATP to the cytoplasmic membrane surface reduced the open state probability in a dose-dependent manner. The channel activity was blocked by quinine and 4-AP but was insensitive to TEA, TTX and amiloride. It is not clear what role this channel might play in the complex electrical activity of β-cells.

Key words

Insulinoma cell line Patch clamp Cation channel Calcium dependence ATP sensitive 

Copyright information

© Springer-Verlag 1987

Authors and Affiliations

  • N. C. Sturgess
    • 1
  • C. N. Hales
    • 2
  • M. L. J. Ashford
    • 1
  1. 1.Department of PharmacologyUniversity of CambridgeCambridgeUK
  2. 2.Department of Clinical BiochemistryNew Addenbrooke's HospitalCambridgeUK

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