In this study we analysed the changes in the properties of rat cerebral cortex Na+/K+-ATPase in streptozotocin induced diabetes (STZ-diabetes). Special attempt was made to determine whether insulin treatment of diabetic animals could restore the altered parameters of this enzyme. Na+/K+-ATPase activity was found to be decreased by 15% after 2 weeks, and by 37% after 4 weeks in diabetic rat brains with a parallel decrease in maximal capacity of low affinity ouabain binding sites. There was no significant change in the high affinity ouabain binding sites. The Kd values did not change significantly. Western blot analysis of brain Na+/K+-ATPase isoforms indicated a 61 ± 5.8% and 20 ± 2.8% decrease of the α1 and α3 isoforms, respectively in 4 weeks diabetic animals. Change in the amount of the α2 isoform proved to be less characteristic. Both types of β subunit isoform showed a significant decrease in four weeks diabetic rats. Our data indicate a good correlation in diabetic rats between changes in Na+/K+-ATPase activity, low affinity ouabain binding capacity and the level of α1 isoform. While insulin treatment of diabetic animals restored the blood glucose level to normal, a complete reversal of diabetes induced changes in Na+/K+-ATPase activity, ouabain binding capacity and Na+/K+-ATPase isoform composition could not be achieved.
ASJC Scopus subject areas
- Cell Biology