Background: Alterations in intracellular Na+ and Ca2+ have been observed in patients with Duchenne muscular dystrophy (DMD) and in animal models of DMD, and inhibition of Na+-H+ exchanger 1 (NHE1) by rimeporide has previously demonstrated cardioprotective effects in animal models of myocardial ischemia and heart failure. Since heart failure is becoming a predominant cause of death in DMD patients, this study aimed to demonstrate a cardioprotective effect of chronic administration of rimeporide in a canine model of DMD.
Methods: Golden retriever muscular dystrophy (GRMD) dogs were randomized to orally receive rimeporide (10 mg/kg, twice a day) or placebo from 2 months to 1 year of age. Left ventricular (LV) function was assessed by conventional and advanced echocardiography.
Results: Compared with placebo-treated GRMD, LV function deterioration with age was limited in rimeporide-treated GRMD dogs as indicated by the preservation of LV ejection fraction as well as overall cardiac parameters different from placebo-treated dogs, as revealed by composite cardiac scores and principal component analysis. In addition, principal component analysis clustered rimeporide-treated GRMD dogs close to healthy control dogs.
Conclusions: Chronic administration of the NHE1 inhibitor rimeporide exerted a protective effect against LV function decline in GRMD dogs. This study provides proof of concept to explore the cardiac effects of rimeporide in DMD patients.
Keywords: Canine model of Duchenne muscular dystrophy; Echocardiography; Left ventricular function; Na(+)-H(+) exchanger isoform 1; Rimeporide.
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