Tissue-specific modulation of Na, K-ATPase α-subunit gene expression in uremic rats

Abstract

Chronic renal failure in the rat is associated with an impaired extrarenal potassium handling, whereas a renal adaptive mechanism of the remaining nephrons has been described. To understand the molecular basis of potassium homeostasis during renal failure we investigated the in vitro pump activity and the catalytic mRNA transcription in three different tissues: skeletal muscle, isolated adipocytes and kidney. The activity of the sodium pump, as measured by ouabain-sensitive 86Rb/K uptake in isolated adipocytes and skeletal muscle fibers, revealed a significant reduction of the pump activity in uremic rats. The reduction of the Na, K-ATPase activity in adipose tissue was associated with a similar decrement of both catalytic subunits (α1 and α2), whereas in the skeletal muscle tissue was only related to a decrease in the activity of the α1 isoform. The expression of rat Na, K-ATPase catalytic isoforms mRNAs in kidney, muscle and adipose tissue from control and chronic renal failure rats