Store depletion triggers the calcium release-activated calcium current (ICRAC) in macrovascular endothelial cells: a comparison with Jurkat and embryonic kidney cell lines.
In endothelial cells, different types of Ca2+ conductances have been described, but none of them has been clearly identified as ICRAC, the Ca2+ release-activated Ca2+ current originally described in mast and lymphoma cells. Here we show that in bovine pulmonary artery endothelial cells (CPAE) depletion of intracellular Ca2+ stores by inositol 1,4,5-trisphosphate (InsP3), Ca2+ ionophores and Ca2+ pump inhibitors activates a Ca2+-selective conductance in the presence of the Ca2+ chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N', N'-tetraacetic acid (BAPTA). The current shows inward rectification, a highly positive reversal potential and is blocked by micromolar concentrations of La3+. The conditions used in studies of endothelial cells were also employed in those of HEK-293, an embryonic kidney cell line commonly used to express putative store-operated channels, and Jurkat cells, the reference cell model. Similar to CPAE, HEK cells also have an ICRAC-like current. At 0 mV holding potential the estimated current density is -0.1 and -0.2 pA/pF in CPAE and HEK cells respectively, i.e. 15 and 30% of that measured in Jurkat cells. As shown in studies of Jurkat cells, larger Na+ currents are detectable in CPAE and HEK cells following store depletion in Ca2+- and Mg2+-free medium. The current carried by Na+ ions is similarly blocked by micromolar La3+, is inwardly rectifying and has a positive reversal potential.
Fasolato
C
C
Dipartimento di Scienze Biomediche Sperimentali, CNR Centro di Studio delle Biomembrane, Università di Padova, Via G. Colombo 3, I-35121 Padua, Italy.
Nilius
B
B
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology*; D002417:Cattle; D002460:Cell Line; D004553:Electric Conductivity; D004622:Embryo, Mammalian; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000494:pharmacology; D015759:Ionomycin / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D019169:Jurkat Cells / Q000502:physiology*; D007668:Kidney / Q000502:physiology*; D007811:Lanthanum / Q000494:pharmacology; D011651:Pulmonary Artery; D015222:Sodium Channels / Q000502:physiology
D015220:Calcium Channels; D007476:Ionophores; D015222:Sodium Channels; D015759:Ionomycin; D007811:Lanthanum; D015544:Inositol 1,4,5-Trisphosphate; D002118:Calcium