Hormonal and neurogenic control of Na-K-ATPase and myosin isoforms in neonatal rat cardiac myocytes

Am J Physiol. 1997 Aug;273(2 Pt 1):C489-99. doi: 10.1152/ajpcell.1997.273.2.C489.

Abstract

In the rat heart there is a postnatal switch in the expression of isoforms of both Na-K-ATPase and myosin heavy chain (MHC). Here we investigated factors controlling isoform changes in cultures of neonatal cardiomyocytes. In serum-free medium, the compositions of either Na-K-ATPase or MHC isoforms resembled the neonatal phenotype. Thyroid hormone induced the MHC isoform switch but increased expression of all Na-K-ATPase isoforms to various extents. Dexamethasone failed to induce the MHC switch and inhibited Na-K-ATPase alpha 1 isoform expression without inducing the other isoforms. With both hormones, the adult phenotype for both MHC and Na-K-ATPase was seen but with low Na-K-ATPase alpha 2. The paucity of alpha 2 protein was not predicted by studies of mRNA levels. In serum, there was a gradual decline of Na-K-ATPase alpha 3 and the appearance of alpha 2, but again at a relatively low level. Expression of Na-K-ATPase alpha 2 was significantly upregulated when cardiomyocytes were cocultured with sympathetic neurons from superior cervical ganglia, without changes in the MHC isoforms. Thus innervation is postulated to play a specific role in modulating Na-K-ATPase gene expression.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Animals, Newborn / physiology*
  • Blood Physiological Phenomena
  • Cells, Cultured
  • Dexamethasone / pharmacology
  • Glucocorticoids / pharmacology
  • Hormones / physiology*
  • Isoenzymes / metabolism
  • Isomerism
  • Myocardium / cytology
  • Myocardium / metabolism*
  • Myosins / metabolism*
  • Rats
  • Rats, Inbred Strains
  • Sodium-Potassium-Exchanging ATPase / metabolism*
  • Sympathetic Nervous System / physiology*
  • Triiodothyronine / pharmacology

Substances

  • Glucocorticoids
  • Hormones
  • Isoenzymes
  • Triiodothyronine
  • Dexamethasone
  • Myosins
  • Sodium-Potassium-Exchanging ATPase