Ca2+ uptake through voltage-gated L-type Ca2+ channels by polarized enterocytes from Atlantic cod Gadus morhua

J Membr Biol. 1998 Aug 1;164(3):229-37. doi: 10.1007/s002329900408.

Abstract

The presence and localization of voltage-gated Ca2+ channels of L-type were investigated in intestinal cells of the Atlantic cod. Enterocytes were loaded with the fluorescent Ca2+ probe, fure-2/AM and changes in intracellular Ca2+ concentrations ([Ca2+]i) were measured, in cell suspensions, in the presence of high potassium levels (100 mm), BAY K-8644 (5 microM), nifedipine (5 microM) or omega-conotoxin (1 microM). L-type Ca2+ channels were visualized on intestinal sections using the fluorescent dihydropyridine (-)-STBodipy. Depolarization of the plasma membrane produced a rapid (within 5 sec) and transient (at basal levels after 21 sec) increase in [Ca2+]i. BAY K-8644 increased the [Ca2+]i by 7.2%. Cells in a Ca2+-free buffer increased [Ca2+]i after addition of 10 mm Ca2+, and this increase was abolished by nifedipine in both depolarizing and normal medium but not by omega-conotoxin. Single cell experiments using video microscopy revealed that enterocytes remained polarized several hours after preparation and that the Ca2+ entry and extrusion occurred at specific and different regions of the enterocyte outer membrane. Fluorescent staining of L-type Ca2+ channels in the intestinal mucosa showed the most intense staining at the brushborder membrane. These results demonstrate the presence of voltage gated L-type Ca2+ channels in enterocytes from the Atlantic cod. The channels are mainly located at the apical side of the cells, and there is a polarized uptake of Ca2+ into the enterocytes. This suggests that the L-type Ca2+ channels are involved in the transcellular Ca2+ entry into the enterocytes.

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
  • Calcium / metabolism*
  • Calcium Channel Agonists / pharmacology
  • Calcium Channel Blockers / pharmacology
  • Calcium Channels / metabolism*
  • Cell Polarity
  • Cells, Cultured
  • Female
  • Fishes
  • Fluorescent Dyes
  • Intestinal Mucosa / metabolism*
  • Intestinal Mucosa / ultrastructure
  • Ion Channel Gating / physiology*
  • Kinetics
  • Male
  • Membrane Potentials
  • Microscopy, Video
  • Microvilli / metabolism
  • Spectrometry, Fluorescence

Substances

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