Effect of thyroid hormone on the distribution and activity of Na, K-ATPase in ventricular myocardium

Arch Biochem Biophys. 2008 Jul 15;475(2):121-7. doi: 10.1016/j.abb.2008.04.019. Epub 2008 Apr 22.

Abstract

Employing detergent-free sucrose-density gradient fractionation method we isolated cholesterol-rich lighter membrane fractions containing approximately 10% of protein, approximately 30% of cholesterol in membranes of ventricular myocardium. Cholesterol-rich lighter membrane fractions contain >70% of Na, K-ATPase and caveolins 1 and 3 and <10% of beta-actin. Treatment of hypothyroid rats with T(3) increased the relative abundance of both alpha1 and beta1 Na, K-ATPase subunits in total membranes by 4- to 5-fold (with no change in caveolin-3), and resulted in 1.9-fold increase in enzyme activity. T(3)-induced Na, K-ATPase subunits were preferentially distributed to the lighter fractions (#s 4, 5 and 6); and increased abundance of alpha1 and beta1 were 34-70% and 43-68%, respectively. We conclude that the activity of Na, K-ATPase is not uniform in cardiac membranes, and while a significant amount of Na, K-ATPase is present in cardiac cholesterol-rich membrane fractions, the intrinsic activity is significantly less than the enzyme present in relatively cholesterol-poor membranes.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Actins / analysis
  • Animals
  • Caveolin 1 / analysis
  • Caveolin 3 / analysis
  • Cell Fractionation
  • Cholesterol / analysis
  • Heart Ventricles / enzymology
  • Hyperthyroidism / chemically induced
  • Hypothyroidism / chemically induced
  • Myocardium / enzymology*
  • Rats
  • Sodium-Potassium-Exchanging ATPase / analysis
  • Sodium-Potassium-Exchanging ATPase / metabolism*
  • Thyroid Hormones / pharmacology*
  • Thyroxine
  • Tissue Distribution
  • Triiodothyronine / pharmacology
  • Uracil / analogs & derivatives
  • Uracil / pharmacology

Substances

  • Actins
  • Caveolin 1
  • Caveolin 3
  • Thyroid Hormones
  • Triiodothyronine
  • 6-n-propyluracil
  • Uracil
  • Cholesterol
  • Sodium-Potassium-Exchanging ATPase
  • Thyroxine