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Sodium hydrogen exchange 1 (NHE-1) regulates connexin 43 expression in cardiomyocytes via reverse mode sodium calcium exchange and c-Jun NH2-terminal kinase-dependent pathways.
- Source :
-
The Journal of pharmacology and experimental therapeutics [J Pharmacol Exp Ther] 2008 Oct; Vol. 327 (1), pp. 105-13. Date of Electronic Publication: 2008 Jul 23. - Publication Year :
- 2008
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Abstract
- Connexin 43, the major connexin isoform in gap junctions of cardiac ventricular myocytes, undergoes changes in distribution and expression in cardiac diseases. The Na(+)-H(+) exchanger (NHE-1), a key mediator of hypertrophy and heart failure, has been shown to be localized in the cardiomyocyte gap junctional regions; however, whether NHE-1 regulates gap junction proteins in the hypertrophied cardiomyocyte is not known. To address this question, neonatal rat ventricular myocytes were treated with phenylephrine (PE) for 24 h to induce hypertrophy. Increased Cx43 expression observed with PE treatment (132.4 +/- 6.3% compared to control; P < 0.05) was further significantly augmented by the specific NHE-1 inhibitor EMD87580 [N-[2-methyl-4,5-bis(methylsulfonyl)-benzoyl]-guanidine hydrochloride] (173.2 +/- 8.7% increase compared to control; P < 0.05 versus PE), an effect that was mimicked by another NHE-1 inhibitor cariporide [4-isopropyl-3-(methylsulfonyl)benzoyl-guanidine methanesulfonate]. PE-induced hypertrophy was associated with mitogen-activated protein kinase c-Jun NH(2)-terminal kinase (JNK) 1/2 activation, whereas inhibition of JNK1/2 with either SP600125 [anthra(1,9-cd)pyrazol-6(2H)-one 1,9-pyrazoloanthrone] or small interfering RNA significantly increased PE-induced up-regulation of Cx43 protein levels. Inhibition of reverse mode Na(+)-Ca(2+) exchange (NCX) with KB-R7943 [2-[2-[4-(4-nitrobenzyloxy)phenyl]ethyl]isothiourea mesylate] partially reversed JNK1/2 activation (195.2 +/- 21.4 versus 143.7 +/- 14.4% with KB-R7943; P < 0.05) and augmented up-regulation of Cx43 protein (121.1 +/- 8.3 versus 215.9 +/- 25.6% with KB-R7943; P < 0.05) in the presence of PE. Our results demonstrate that NHE-1 negatively regulates Cx43 protein expression in PE-induced cardiomyocyte hypertrophy via a JNK1/2-dependent pathway, which is probably activated by reverse mode NCX activity.
- Subjects :
- Animals
Cells, Cultured
Connexin 43 analysis
Phenylephrine pharmacology
Rats
Rats, Sprague-Dawley
Sodium-Hydrogen Exchangers antagonists & inhibitors
Connexin 43 genetics
Mitogen-Activated Protein Kinase 8 physiology
Mitogen-Activated Protein Kinase 9 physiology
Myocytes, Cardiac metabolism
Sodium-Calcium Exchanger physiology
Sodium-Hydrogen Exchangers physiology
Subjects
Details
- Language :
- English
- ISSN :
- 1521-0103
- Volume :
- 327
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- The Journal of pharmacology and experimental therapeutics
- Publication Type :
- Academic Journal
- Accession number :
- 18650245
- Full Text :
- https://doi.org/10.1124/jpet.108.140228