Endothelin-1 induced hypertrophic effect in neonatal rat cardiomyocytes: involvement of Na+/H+ and Na+/Ca2+ exchangers

J Mol Cell Cardiol. 2006 Nov;41(5):807-15. doi: 10.1016/j.yjmcc.2006.05.016. Epub 2006 Jul 21.

Abstract

Endothelin-1 (ET-1) is a potent agonist of cell growth that also stimulates Na(+)/H(+) exchanger isoform 1 (NHE-1) activity. It was hypothesized that the increase in intracellular Na(+) ([Na(+)](i)) mediated by NHE-1 activity may induce the reverse mode of Na(+)/Ca(2+) exchanger (NCX(rev)) increasing intracellular Ca(2+) ([Ca(2+)](i)) which in turn will induce hypertrophy. The objective of this work was to test whether the inhibition of NHE-1 or NCX(rev) prevents ET-1 induced hypertrophy in neonatal rat cardiomyocytes (NRVMs). NRVMs were cultured (24 h) in the absence (control) and presence of 5 nmol/L ET-1 alone, or combined with 1 mumol/L HOE 642 or 5 mumol/L KB-R7943. Cell surface area, (3)H-phenylalanine incorporation and atrial natriuretic factor (ANF) mRNA expression were increased to 131 +/- 3, 220 +/- 12 and 190 +/- 25% of control, respectively (P < 0.05) by ET-1. [Na(+)](i) and total [Ca(2+)](i) were higher (8.1 +/- 1.2 mmol/L and 636 +/- 117 nmol/L, respectively) in ET-1-treated than in control NRVMs (4.2 +/- 1.3 and 346 +/- 85, respectively, P < 0.05), effects that were cancelled by NHE-1 inhibition with HOE 642. The rise in [Ca(2+)](i) induced by extracellular Na(+) removal (NCX(rev)) was higher in ET-1-treated than in control NRVMs and the effect was prevented by co-treatment with HOE 642 or KB-R7943 (NCX(rev) inhibitor). The ET-1-induced increase in cell area, ANF mRNA expression and (3)H-phenylalanine incorporation in ET-1-treated NRVM were decreased by NHE-1 or NCX(rev) inhibition. Our results provide the first evidence that NCX(rev) is, secondarily to NHE-1 activation, involved in ET-1-induced hypertrophy in NRVMs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Newborn*
  • Atrial Natriuretic Factor / metabolism
  • Cardiomegaly / metabolism*
  • Endothelin-1 / pharmacology*
  • Myocytes, Cardiac / drug effects
  • Myocytes, Cardiac / metabolism*
  • Myocytes, Cardiac / pathology
  • RNA, Messenger / metabolism*
  • Rats
  • Rats, Wistar
  • Sodium-Calcium Exchanger / metabolism*
  • Sodium-Hydrogen Exchangers / metabolism*

Substances

  • Endothelin-1
  • RNA, Messenger
  • Sodium-Calcium Exchanger
  • Sodium-Hydrogen Exchangers
  • growth factor-activatable Na-H exchanger NHE-1
  • Atrial Natriuretic Factor