Inhibition of Na+,K+-ATPase activity in cultured rat cerebellar granule cells prevents the onset of apoptosis induced by low potassium (original) (raw)

2000, Neuroscience Letters

In cerebellar granule cells in culture, lowering of extracellular [K 1 ] results in apoptotic death (D'Mello, S.R., Galli, C., Ciotti, T. and Calissano, P., Induction of apoptosis in cerebellar granule neurons by low potassium: inhibition of death by insulin-like growth factor I and cAMP, Proc. Natl. Acad. Sci. USA, 90 (1993) 10989-10993). In this model, we studied the in¯uence of Na 1 ,K 1 -ATPase inhibition on apoptosis. We demonstrate that cell death (93^2 vs. 46^1.6%) as well as fragmentation of nuclear DNA induced by low extracellular potassium were prevented by addition of ouabain (0.1 mM), a speci®c inhibitor of the Na 1 ,K 1 -ATPase. Blockade of glutamatergic N-methyl-d-aspartate and alpha-amino-3-hydroxy-5methyl-4-isoxazole propionic acid receptors by 5-methyl-10,11-dihydro-5H-dibenzo(a,d)cyclohepten-5,10-imine hydrogen maleate (MK-801; 20 mM) and 6-Cyano-7-nitroquinoxaline-2,3-dione (CNQX; 50 mM) did not inhibit the protective effect of ouabain. 24 h treatment with ouabain also decreased cell death induced by Fe 21 /ascorbic acid (74^2% to 493 %). We speculate that ouabain pretreatment enhances the resistance against low [K 1 ]-induced apoptosis independent of glutamate-receptor activation. Since this effect can be mimicked by a free-radical generating system, we suggest an antioxidative effect underlying ouabain-induced neuroprotection. q