Basic Science and Experimental Studies
Cardiac Contractility Modulation Electrical Signals Normalize Activity, Expression, and Phosphorylation of the Na+-Ca2+ Exchanger in Heart Failure

https://doi.org/10.1016/j.cardfail.2008.08.011Get rights and content

Abstract

Background

Expression and phosphorylation of the cardiac Na+-Ca2+ exchanger-1 (NCX-1) are up-regulated in heart failure (HF). We examined the effects of chronic cardiac contractility modulation (CCM) therapy on the expression and phosphorylation of NCX-1 and its regulators GATA-4 and FOG-2 in HF dogs.

Methods and Results

Studies were performed in LV tissue from 7 CCM-treated HF dogs, 7 untreated HF dogs, and 6 normal (NL) dogs. mRNA expression of NCX-1, GATA-4, and FOG-2 was measured using reverse transcriptase polymerase chain reaction, and protein level was determined by Western blotting. Phosphorylated NCX-1 (P-NCX) was determined using a phosphoprotein enrichment kit. Compared with NL dogs, NCX-1 mRNA and protein expression and GATA-4 mRNA and protein expression increased in untreated HF dogs, whereas FOG-2 expression decreased. Compared with NL dogs, the level of P-NCX-1 normalized to total NCX-1 increased in untreated HF dogs (0.80 ± 0.10 vs 0.37 ± 0.04; P < .05). CCM therapy normalized NCX-1 expression, GATA-4, and FOG-2 expression, and the ratio of P-NCX-1 to total NCX-1 (0.62 ± 0.10).

Conclusion

Chronic monotherapy with CCM restores expression and phosphorylation of NCX-1. These findings are consistent with previous observations of improved LV function and normalized sarcoplasmic reticulum calcium cycling in the left ventricles of HF dogs treated with CCM therapy.

Section snippets

Materials

Dogs were purchased from Marshal Farms (North Rose, NY). Chemicals and supplies for electrophoresis and electrotransfer were purchased from Bio-Rad (Hercules, CA). Biochemical supplies were obtained from Sigma Chemical (St Louis, MO). Gene primers were synthesized by Operon Technologies, Inc (Alameda, CA). Primary antibodies for NCX-1 and calsequestrin (CSQ) were obtained from ABR, Inc (Golden, CO), and primary antibodies for Fog-2 and GATA-4 were obtained from Santa Cruz Biotechnologies, Inc

Results

The hemodynamic results obtained in all dogs included in this study have been reported.42 Briefly, in sham-operated HF control dogs, LV ejection fraction measured angiographically decreased from 27% ± 1% to 23% ± 1% during the 3 months of follow-up (P = .001). In contrast, LV ejection fraction increased from 27% ± 1% before initiating CCM therapy to 33% ± 1% after 3 months of CCM therapy (P = .0001).20

Discussion

CCM electrical signals delivered to the myocardium during the absolute refractory period have been shown to improve LV function both when delivered acutely and after long-term delivery in dogs with experimentally induced HF.4, 14, 40 In HF dogs, CCM therapy was associated with improved SR calcium cycling, as evidenced by increased activity and expression of calcium-ATPase and increased phosphorylation of phospholamban.40 CCM therapy in patients with chronic HF (New York Heart Association class

Conclusions

The results of the present study indicate that long-term therapy with CCM electric signals normalize the NCX-1, GATA-4, and FOG-2 signaling pathway in HF dogs. Normalization of components of this signaling pathway is consistent with and provides further support to previous observations of improved SR calcium cycling in HF dogs treated long-term with CCM electrical signals. These improvements in NCX-1 also represent a potential contributing factor to the improved LV function in HF.

References (54)

  • P. Mansier et al.

    Isolation of impermeable inside-out vesicles from an enriched sarcolemma fraction of rat heart

    J Biol Chem

    (1983)
  • R.C. Gupta et al.

    Reduced sarcoplasmic reticulum Ca(2+)-uptake and expression of phospholamban in left ventricular myocardium of dogs with heart failure

    J Mol Cell Cardiol

    (1999)
  • S. Mishra et al.

    Molecular mechanisms of reduced sarcoplasmic reticulum Ca(2+) uptake in human failing left ventricular myocardium

    J Heart Lung Transplant

    (2002)
  • M. Imai et al.

    Therapy with cardiac contractility modulation electrical signals improves left ventricular function and remodeling in dogs with chronic heart failure

    J Am Coll Cardiol

    (2007)
  • A. Hjalmarson et al.

    Effects of controlled-release metoprolol on total mortality, hospitalizations, and well-being in patients with heart failure: the Metoprolol CR/XL Randomized Intervention Trial in congestive heart failure (MERIT-HF). MERIT-HF Study Group

    JAMA

    (2000)
  • B. Pitt et al.

    The effect of spironolactone on morbidity and mortality in patients with severe heart failure. Randomized Aldactone Evaluation Study Investigators

    N Engl J Med

    (1999)
  • Investigators. Effect of Enalapril on survival in patient with reduced left ventricular ejection fraction and congestive heart failure

    N Engl J Med

    (1991)
  • H. Morita et al.

    Long- term effects of non-excitatory cardiac contractility modulation electric signals on the progression of heart failure in dogs

    Eur J Heart Fail

    (2004)
  • M. Packer et al.

    Effect of oral milrinone on mortality in severe chronic heart failure. The PROMISE Study Research Group

    N Engl J Med

    (1991)
  • A. Auricchio et al.

    Effect of pacing chamber and atrioventricular delay on acute systolic function of paced patients with congestive heart failure. The Pacing Therapies for Congestive Heart Failure Study Group. The Guidant Congestive Heart Failure Research Group

    Circulation

    (1999)
  • A. Auricchio et al.

    The Pacing Therapies for Congestive Heart Failure (PATH-CHF) study: rationale, design, and endpoints of a prospective randomized multicenter study

    Am J Cardiol

    (1999)
  • J.J. Blanc et al.

    Evaluation of different ventricular pacing sites in patients with severe heart failure: results of an acute hemodynamic study

    Circulation

    (1997)
  • D. Gras et al.

    Multisite pacing as a supplemental treatment of congestive heart failure: preliminary results of the Medtronic Inc. InSync Study

    Pacing Clin Electrophysiol

    (1998)
  • D.A. Kass et al.

    Improved left ventricular mechanics from acute VDD pacing in patients with dilated cardiomyopathy and ventricular conduction delay

    Circulation

    (1999)
  • L.A. Saxon et al.

    Biventricular pacing in patients with congestive heart failure: two prospective randomized trials. The VIGOR CHF and VENTAK CHF

    Investigators. Am J Cardiol

    (1999)
  • C. Pappone et al.

    First human chronic experience with cardiac contractility modulation by nonexcitatory electrical currents for treating systolic heart failure: mid-term safety and efficacy results from a multicenter study

    J Cardiovasc Electrophysiol

    (2004)
  • H.N. Sabbah et al.

    Treating heart failure with cardiac contractility modulation electrical signals

    Curr Heart Fail Rep

    (2006)
  • Cited by (19)

    • Role of the dysfunctional ryanodine receptor - Na<sup>+</sup>-Ca<sup>2+</sup>exchanger axis in progression of cardiovascular diseases: What we can learn from pharmacological studies?

      2016, European Journal of Pharmacology
      Citation Excerpt :

      Again, CamKII-dependent signaling is implicated in connecting the increased neurohormonal activation to the abnormal Ca2+-dependent regulation of cell function (Mollova et al., 2015). Accordingly, involvement of NCX upregulation and altered phosphorylation status play a key function in remodeling (Gupta et al., 2009; Katanosaka et al., 2007; Valdivia et al., 2015). Similar role of NCX in pathogenesis of atrial remodeling associated with atrial fibrillation has also been reported (see below).

    • Effects of acute intravenous infusion of apelin on left ventricular function in dogs with advanced heart failure.

      2013, Journal of cardiac failure
      Citation Excerpt :

      MVO2 was determined as the product of total coronary blood flow and aorta to coronary sinus O2 difference. Sodium dodecyl sulfate (SDS) extracts of ∼100 mg frozen LV tissue specimens from 6 NL and 6 HF dogs were prepared, and protein was assayed as previously described in detail.22,23 For Western blotting, ∼50 μg protein was loaded on precast 4%–20% SDS-polyacrylamide gel electrophoresis gels (Bio-Rad) for APJ or 150 μg protein was loaded on 10%–20% Tris-Tricine precast gels (Bio-Rad) for APLN after denaturation in reducing sample buffer for 10 minutes at 95°C.

    • Cardiac Contractility Modulation in Heart Failure: Mechanisms and Clinical Evidence

      2020, Current Treatment Options in Cardiovascular Medicine
    View all citing articles on Scopus
    View full text