Regulation of na⁺, k⁺-atpase gene expression by insulin in vascular smooth muscle cells

Na⁺, K⁺-ATPase gene expression and activity and its modulation by insulin were investigated in vascular smooth muscle cells (VSMC). Messenger RNAs encoding for αand α2-isoforms of Na⁺, K⁺- ATPase were identified in a pure population of cultured VSMC (a7r5 cells). The predominant isoform in VSMC was alf but only α2 was regulated by insulin. Insulin treatment of VSMC for 1 and 6 h caused significant increases in mRNA encoding the α2-subunit of Na⁺, K⁺-ATPase (n = 7, P <.01). Under similar conditions, insulin had no effect on a:1-Na⁺, K⁺-ATPase mRNA levels. VSMC treated with insulin exhibited a significant stimulation of ouabain inhibitable ATPase activity (1 h insulin, n = 3, v control, n = 3, P <.025; 6 h insulin, n = 3, v control, n = 3, P <.05). Changes in insulin regulation of Na⁺, K⁺-ATPase gene expression in vascular smooth muscle may be an important factor in the development of hypertension in diabetes. Am J Hypertens.