Ca2+ stores in the chick embryo retina cells.
The Ca2+ stores of digitonin permeabilized chick embryo retina cells in culture were characterized, by using the fluorescence of Fluo-3 potassium salt to follow continuously the free [Ca2+] in the medium. After ATP dependent Ca2+ accumulation, the Ca2+ release was induced by several agents; 10 microM cyclic-ADP-ribose (cADPR), 40 microM Ins (1,4,5)P3 10 microM thapsigargin (Th), 25 microM ionomycin (Ion), 15 microM CCCP together with 4.5 micrograms/ml oligomycin (CCCP/Olig), 50 microM arachidonic acid (AA). Neither Ins(1,4,5)P3 nor cADPR were able to mobilize Ca2+ from internal stores in these cells, but Th and AA were effective in releasing Ca2+. Four major Ca2+ stores in chick embryo retina cells were distinguished: i) the thapsigargin sensitive Ca2+ store, most likely the ER; ii) the Ca2+ store sensitive to oligomycin and CCCP, most likely the mitochondrial Ca2+ store, iii) an AA sensitive Ca2+ store, which is distinct from the previous two; and, iv) the Ca2+ store only sensitive to ionomycin. The capacities of these different Ca2+ stores of the chick embryo retina cells, relative to the total intracellular stores, are: 63.3%, 14.1%, 8.2%, for the ER, the mitochondrial and for the AA sensitive Ca2+ stores, respectively.
Cristóvão
A J
AJ
Center for Neuroscience of Coimbra, University of Coimbra, Portugal. ajcristovao@gemini.ci.vc.pt
Capela
A N
AN
Carvalho
C M
CM
D000246:Adenosine Diphosphate Ribose / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D016718:Arachidonic Acid / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002463:Cell Membrane Permeability; D002642:Chick Embryo; D036563:Cyclic ADP-Ribose; D004072:Digitonin / Q000737:chemistry; D007202:Indicators and Reagents / Q000737:chemistry; D015544:Inositol 1,4,5-Trisphosphate / Q000494:pharmacology; D015759:Ionomycin / Q000494:pharmacology; D009840:Oligomycins / Q000494:pharmacology; D012160:Retina / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D019284:Thapsigargin / Q000494:pharmacology
D007202:Indicators and Reagents; D009840:Oligomycins; D036563:Cyclic ADP-Ribose; D000246:Adenosine Diphosphate Ribose; D016718:Arachidonic Acid; D015759:Ionomycin; D019284:Thapsigargin; D015544:Inositol 1,4,5-Trisphosphate; D004072:Digitonin; D002118:Calcium