Voltage-gated Ca2+ currents in rat gastric enterochromaffin-like cells

Am J Physiol. 1998 Feb;274(2):C424-9. doi: 10.1152/ajpcell.1998.274.2.C424.

Abstract

Enterochromaffin-like (ECL) cells are histamine-containing endocrine cells in the gastric mucosa that maintain a negative membrane potential of about -50 mV, largely due to voltage-gated K+ currents [D. F. Loo, G. Sachs, and C. Prinz. Am. J. Physiol. 270 (Gastrointest Liver Physiol. 33): G739-G745, 1996]. The current study investigated the presence of voltage-gated Ca2+ channels in single ECL cells. ECL cells were isolated from rat fundic mucosa by elutriation, density gradient centrifugation, and primary culture to a purity > 90%. Voltage-gated Ca2+ currents were measured in single ECL cells using the whole cell configuration of the patch-clamp technique. Depolarization-activated currents were recorded in the presence of Na+ or K+ blocking solutions and addition of 20 mM extracellular Ca2+. ECL cells showed inward currents in response to voltage steps that were activated at a test potential of around -20 mV with maximal inward currents observed at +20 mV and 20 mM extracellular Ca2+. The inactivation rate of the current decreased with increasingly negative holding potentials and was totally abolished at a holding potential of -30 mV. Addition of extracellular 20 mM Ba2+ instead of 20 mM Ca2+ increased the depolarization-induced current and decreased the inactivation rate. The inward current was fully inhibited by the specific L-type Ca2+ channel inhibitor verapamil (0.2 mM) and was augmented by the L-type Ca2+ channel activator BAY K 8644 (0.07 mM). We conclude that depolarization activates high-voltage-activated Ca2+ channels in ECL cells. Activation characteristics, Ba2+ effects, and pharmacological results imply the presence of L-type Ca2+ channels, whereas inactivation kinetics suggest the presence of additional N-type channels in rat gastric ECL cells.

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
  • Barium / metabolism
  • Calcium / metabolism
  • Calcium Channel Agonists / pharmacology
  • Calcium Channel Blockers
  • Calcium Channels / drug effects
  • Calcium Channels / metabolism*
  • Cells, Cultured
  • Enterochromaffin-like Cells / drug effects
  • Enterochromaffin-like Cells / metabolism*
  • Female
  • Gastric Fundus
  • Gastric Mucosa / cytology
  • Histamine / metabolism
  • Patch-Clamp Techniques
  • Rats
  • Rats, Sprague-Dawley
  • Verapamil / pharmacology

Substances

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