The effects of anoxia on cytosolic free calcium, calcium fluxes, and cellular ATP levels in cultured kidney cells.
The effect of anoxia and substrate removal on cytosolic free calcium (Ca2+i), cell calcium, ATP content, and calcium efflux was determined in cultured monkey kidney cells (LLC-MK2) exposed to 95% N2, 5% CO2 for 60 min. In the control period, the basal Ca2+i level was 70.8 +/- 9.4 nM. During 1 h of anoxia without substrate, ATP content decreased 70%, Ca2+i and calcium efflux increased 2.5-fold, while the total cell calcium did not change. When the cells were perfused again with O2 and 5 mM glucose, the ATP concentration, Ca2+i, and calcium efflux returned to control levels within 15-20 min. In the presence of 20 mM glucose, anoxia did not produce any change in ATP, in Ca2+i or in calcium efflux. An important source of calcium contributing to the rise in Ca2+i induced by anoxia appears to be extracellular because the rate of rise in Ca2+i is proportional to the extracellular calcium concentration, and because La3+ which blocks calcium influx greatly reduces the rise in Ca2+i. Mitochondria appear to control Ca2+i as well since the early rise in Ca2+i cannot be blocked by La3+ during the initial phase of anoxia, and since the mitochondrial inhibitor carbonyl cyanide p-trifluoromethoxyphenylhydrazone increases Ca2+i further during reoxygenation and slows the return of Ca2+i to control levels.
D000255:Adenosine Triphosphate / Q000032:analysis*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D002478:Cells, Cultured; D003600:Cytosol / Q000032:analysis / Q000378:metabolism*; D000882:Haplorhini; D007668:Kidney / Q000032:analysis / Q000378:metabolism*; D008274:Magnesium / Q000494:pharmacology; D008928:Mitochondria / Q000502:physiology; D010100:Oxygen; D012964:Sodium / Q000378:metabolism
D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D000255:Adenosine Triphosphate; D012964:Sodium; D008274:Magnesium; D010100:Oxygen; D002118:Calcium