In situ Ca(2+)-induced Ca2+ release from a ryanodine-sensitive intracellular Ca2+ store in corneal epithelial cells.
1. In a number of tissues, Ca2+ signaling involves Ca(2+)-induced Ca2+ release (CICR) from ryanodine- and caffeine-sensitive intracellular Ca2+ stores. We sought evidence for such a mechanism in bovine corneal epithelial cells (BCE). 2. We have identified a microsomal fraction of BCE which possesses high-affinity [3H]-ryanodine binding sites indicating the presence of the ryanodine receptor Ca2+ channel. 3. Functional evidence for CICR is that in fura-2 loaded BCE the magnitude of Ca2+ transients induced by the addition of either the adenylate cyclase activator, forskolin, or the L-type Ca2+ channel agonist, BAY-K 8644, were both enhanced by preincubation with 5 microM ryanodine. This ryanodine enhancement provides evidence that Ca2+ release from a ryanodine-sensitive intracellular Ca2+ store also contributes to the Ca2+ transients. Therefore, Ca(2+)-induced Ca2+ release is a component of Ca2+ signaling in BCE.
Socci
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Department of Physiology and Endocrinology, Medical College of Georgia, Augusta 30912.
Chu
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Reinach
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Mészáros
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LG
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000818:Animals; D001665:Binding Sites; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology*; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D002417:Cattle; D005576:Colforsin / Q000494:pharmacology; D003315:Cornea / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism; D004847:Epithelial Cells; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D009124:Muscle Proteins / Q000187:drug effects / Q000378:metabolism; D011863:Radioimmunoassay; D012433:Ryanodine / Q000378:metabolism / Q000494:pharmacology*; D019837:Ryanodine Receptor Calcium Release Channel; D015398:Signal Transduction
D015220:Calcium Channels; D009124:Muscle Proteins; D019837:Ryanodine Receptor Calcium Release Channel; D012433:Ryanodine; D005576:Colforsin; D002110:Caffeine; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D000242:Cyclic AMP; D002118:Calcium