Effects of partial hepatectomy on the plasma membrane status and the invertor mechanism of the hepatocyte Na,K-ATPase activity regulation in rats of various age.

The experiments were performed on adult (6-8 months) and old (22-24 months) Wistar rats. Insulin induced plasma membrane hyperpolarization and hepatocyte Na,K-ATPase activation in adult but not in old sham-operated rats. Partial hepatectomy had no effect on the invertor mechanism of Na,K-ATPase activity regulation in the liver of adult rats, while pronounced changes took place in old animals 4 weeks after partial hepatectomy. Insulin induced hyperpolarization in hepatocyte plasma membrane and activation of Na,K-ATPase both in old and adult hepatectomized rats. Invertors, intracellular regulators of the plasma membrane status, played an important role in the mechanism of this insulin-induced hyperpolarization. Four weeks after partial hepatectomy in old animals, the invertor mechanism of hepatocyte plasma membrane regulation appeared again, as well as membrane Na,K-ATPase capability to react to insulin action.