Insulin induced translocation of Na+/K+ -ATPase is decreased in the heart of streptozotocin diabetic rats.
Abstract
To investigate the effect of acute insulin administration on the subcellular localization of Na(+)/K(+)-ATPase isoforms in cardiac muscle of healthy and streptozotocin-induced diabetic rats. Membrane fractions were isolated with subcellular fractionation and with cell surface biotinylation technique. Na(+)/K(+)-ATPase subunit isoforms were analysed with ouabain binding assay and Western blotting. Enzyme activity was measured using 3-O-methylfluorescein-phosphatase activity. In control rat heart muscle alpha1 isoform of Na(+)/K(+) ATPase resides mainly in the plasma membrane fraction, while alpha2 isoform in the intracellular membrane pool. Diabetes decreased the abundance of alpha1 isoform (25 %, P<0.05) in plasma membrane and alpha2 isoform (50%, P<0.01) in the intracellular membrane fraction. When plasma membrane fractions were isolated by discontinuous sucrose gradients, insulin-stimulated translocation of alpha2- but not alpha1-subunits was detected. Alpha1-subunit translocation was only detectable by cell surface biotinylation technique. After insulin administration protein level of alpha2 increased by 3.3-fold, alpha1 by 1.37-fold and beta1 by 1.51-fold (P<0.02) in the plasma membrane of control, and less than 1.92-fold (...Continue Reading
References
Citations
Related Concepts
Related Feeds
AKT Pathway
This feed focuses on the AKT serine/threonine kinase, which is an important signaling pathway involved in processes such as glucose metabolism and cell survival.