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Exercise alters the regulation of myocardial Na(+)/H(+) exchanger-1 activity.

Publication ,  Journal Article
Feger, BJ; Starnes, JW
Published in: American journal of physiology. Regulatory, integrative and comparative physiology
November 2013

The myocardial Na(+)/H(+) exchanger-1 (NHE1) plays a major role in regulation of intracellular pH, and its upregulation has been implicated in increased ischemia-reperfusion injury and other pathologies. Hydrogen peroxide (H2O2) increases NHE1 activity acutely via ERK1/2 signaling. Chronic strenuous exercise upregulates NHE1 in skeletal muscle, but we hypothesize this will not occur in the heart, because exercise creates a cardioprotective phenotype. NHE1 activity and its regulation by H2O2 were examined at physiological pH using isolated cardiomyocytes from female Sprague-Dawley rats exercised on a treadmill for 5 wk (E; n = 11). Compared with sedentary (S; n = 15), E displayed increases (P < 0.05) in heart-to-body weight ratio (6.8%) and plantaris mitochondria content (89%). NHE1 activity (acid efflux rate following an acid load) was 209% greater in E (0.65 ± 0.12 vs. 2.01 ± 0.29 fmol/min). The difference was attributed primarily to greater cell volume (22.2 ± 0.6 vs. 34.3 ± 1.1 pl) and intracellular pH-buffering capacity (33.94 ± 1.59 vs. 65.82 ± 5.20 mM/pH unit) of E myocytes. H2O2 stimulation (100 μM) raised NHE1 activity significantly less in E (45%) than S (167%); however, activity remained 185% greater in E. ERK1/2 inhibition abrogated the increases. H2O2-stimulated ERK1/2 phosphorylation levels normalized to total ERK1/2 were similar between groups. Content of NHE1 and activities of H2O2 scavengers were also similar. We observed that intracellular pH-buffering capacity differences between groups became progressively less with declining pH, which may be an exercise-induced cardioprotective adaptation to lower NHE1 activity during certain pathological situations. We conclude that strenuous endurance exercise increases myocardial NHE1 activity at physiological pH, which would likely enhance cardiac performance under physiological conditions.

Duke Scholars

Published In

American journal of physiology. Regulatory, integrative and comparative physiology

DOI

EISSN

1522-1490

ISSN

0363-6119

Publication Date

November 2013

Volume

305

Issue

10

Start / End Page

R1182 / R1189

Related Subject Headings

  • Sodium-Hydrogen Exchangers
  • Sodium-Hydrogen Exchanger 1
  • Signal Transduction
  • Reactive Oxygen Species
  • Rats, Sprague-Dawley
  • Rats
  • Physiology
  • Physical Conditioning, Animal
  • Myocytes, Cardiac
  • Myocardium
 

Citation

APA
Chicago
ICMJE
MLA
NLM
Feger, B. J., & Starnes, J. W. (2013). Exercise alters the regulation of myocardial Na(+)/H(+) exchanger-1 activity. American Journal of Physiology. Regulatory, Integrative and Comparative Physiology, 305(10), R1182–R1189. https://doi.org/10.1152/ajpregu.00228.2013
Feger, Bryan J., and Joseph W. Starnes. “Exercise alters the regulation of myocardial Na(+)/H(+) exchanger-1 activity.American Journal of Physiology. Regulatory, Integrative and Comparative Physiology 305, no. 10 (November 2013): R1182–89. https://doi.org/10.1152/ajpregu.00228.2013.
Feger BJ, Starnes JW. Exercise alters the regulation of myocardial Na(+)/H(+) exchanger-1 activity. American journal of physiology Regulatory, integrative and comparative physiology. 2013 Nov;305(10):R1182–9.
Feger, Bryan J., and Joseph W. Starnes. “Exercise alters the regulation of myocardial Na(+)/H(+) exchanger-1 activity.American Journal of Physiology. Regulatory, Integrative and Comparative Physiology, vol. 305, no. 10, Nov. 2013, pp. R1182–89. Epmc, doi:10.1152/ajpregu.00228.2013.
Feger BJ, Starnes JW. Exercise alters the regulation of myocardial Na(+)/H(+) exchanger-1 activity. American journal of physiology Regulatory, integrative and comparative physiology. 2013 Nov;305(10):R1182–R1189.

Published In

American journal of physiology. Regulatory, integrative and comparative physiology

DOI

EISSN

1522-1490

ISSN

0363-6119

Publication Date

November 2013

Volume

305

Issue

10

Start / End Page

R1182 / R1189

Related Subject Headings

  • Sodium-Hydrogen Exchangers
  • Sodium-Hydrogen Exchanger 1
  • Signal Transduction
  • Reactive Oxygen Species
  • Rats, Sprague-Dawley
  • Rats
  • Physiology
  • Physical Conditioning, Animal
  • Myocytes, Cardiac
  • Myocardium