Is there a calcium paradox in isolated bovine aortic endothelial cells?
When bovine aortic endothelial (BAE) cells are superfused with a solution containing low calcium (approximately 10 nM) and subsequently exposed to a solution containing normal Ca2+ (2 mM) a large transient increase in intracellular calcium is seen. This elevation in [Ca2+]i is similar to that described as the calcium paradox in cardiac cells. If the cells are exposed to the agonist, ATP, during the period in low-Ca2+ solution the paradoxical rise in [Ca2+]i is increased. Removal of external Na+ from the low-Ca2+ solution reduces the rise in [Ca2+]i on returning to 2mM-Ca2+ solution. These data are consistent with the presence of a calcium paradox in these cells and with the hypothesis that the underlying mechanism involves the loading of the cell with Na+ during the period in low Ca2+. This process may occur as a result of the altered selectivity of the ATP-activated Ca2+ influx mechanism.
Gillespie
J I
JI
Department of Physiological Sciences, Medical School, The University, Newcastle upon Tyne.
Johnson
C
C
Nicholls
J
J
Lynch
M
M
Greenwell
J R
JR
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000378:metabolism; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology*; D002417:Cattle; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism; D066298:In Vitro Techniques; D007424:Intracellular Fluid / Q000378:metabolism; D007474:Ion Exchange; D012964:Sodium / Q000378:metabolism
D000255:Adenosine Triphosphate; D012964:Sodium; D002118:Calcium