Acute changes in myo-inositol uptake and 22Na+ flux in murine neuroblastoma cells (N1E-115) following insulin

Abstractmyo-Inositol uptake was investigated in a murine neuroblastoma clone (N1E-115) to determine the effect of altered Na+,K+-ATPase activity. The Na+ ionophone monensin, and veratridine, an alkaloid affecting voltage-dependent Na+ entry, increased acute 22Na+ uptake and 22Na+ efflux from pre-loaded cells, concomitant with enhanced myo-inositol uptake. This effect was also seen following insulin. Insulin-stimulated myo-inositol uptake was inhibited by amiloride, ouabain and pyrithiamine. Amiloride inhibition suggests that activation of Na+/H+ exchange preceding Na+,K+-ATPase activation is involved in insulin stimulation of myo-inositol uptake. Pyrithiamine inhibition is an indication of prior activation of the Na+,K+-ATPase α+ catalytic subunit by insulin. The results provide evidence that insulin contributes to the maintenance of Na+, K+-ATPase in neuronal tissue