ISSN:
1432-1424
Keywords:
Key words: BAY K-8644 — nifedipine — (-)-STBodipy —ω-conotoxin — intestine — teleost
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
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 μm), nifedipine (5 μm) or ω-conotoxin (1 μm). 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 ω-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.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s002329900408
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