T. Matsuda et al., INVOLVEMENT OF NA-CA2+ EXCHANGER IN REPERFUSION-INDUCED DELAYED CELL-DEATH OF CULTURED RAT ASTROCYTES(), European journal of neuroscience, 8(5), 1996, pp. 951-958
In some cells, Ca2+ depletion induces an increase in intracellular Ca2
+ ([Ca2+](i)) after reperfusion with Ca2+-containing solution, but the
mechanism for the reperfusion injury is not fully elucidated. Using a
n antisense strategy we studied the role of the Na+-Ca2+ exchanger in
reperfusion injury in cultured rat astrocytes. When astrocytes were pe
rfused in Ca2+-free medium for 15-60 min, a persistent increase in [Ca
2+](i) was observed immediately after reperfusion with Ca2+-containing
medium, and the number of surviving cells decreased 3-5 days latter.
The increase in [Ca2+](i) was enhanced by low extracellular Na+ ([Na+]
(0)) during reperfusion and blocked by the inhibitors of the Na+-Ca2exchanger amiloride and 3,4-dichlorobenzamil, but not by the Ca2+ chan
nel antagonists nifedipine, Cd2+ and Ni2+. Treatment of astrocytes wit
h antisense, but not sense, oligodeoxynucleotide to the Na+-Ca2+ excha
nger decreased Na+-Ca2+ exchanger protein level and exchange activity.
The antisense oligomer attenuated reperfusion-induced increase in [Ca
2+](i) and cell toxicity. The Na+-Ca2+ exchange inhibitors 3,4-dichlor
obenzamil and ascorbic acid protected astrocytes from reperfusion inju
ry partially, while the stimulators sodium nitroprusside and 8-bromo-c
yclic GMP and low [Na+](0) exacerbated the injury. Pretreatment of ast
rocytes with ouabain and monensin caused similar delayed glial cell de
ath. These findings suggest that Ca2+ entry via the Na+-Ca2+ exchanger
plays an important role in reperfusion-induced delayed glial cell dea
th.