Regional evidence of modulation of cardiac adiponectin level in dilated cardiomyopathy: pilot study in a porcine animal model

BACKGROUND: The role of systemic and myocardial adiponectin (ADN) in dilated cardiomyopathy is still debated. We tested the regulation of both systemic and myocardial ADN and the relationship with AMP-activated protein kinase (AMPK) activity in a swine model of non-ischemic dilated cardiomyopathy. METHODS AND RESULTS: Cardiac tissue was collected from seven instrumented adult male minipigs by pacing the left ventricular (LV) free wall (180 beats/min, 3 weeks), both from pacing (PS) and opposite sites (OS), and from five controls. Circulating ADN levels were inversely related to global and regional cardiac function. Myocardial ADN in PS was down-regulated compared to control (p < 0.05), yet ADN receptor 1 was significantly up-regulated (p < 0.05). No modifications of AMPK were observed in either region of the failing heart. Similarly, myocardial mRNA levels of PPARγ, PPARα, TNFα, iNOS were unchanged compared to controls. CONCLUSIONS: Paradoxically, circulating ADN did not show any cardioprotective effect, confirming its role as negative prognostic biomarker of heart failure. Myocardial ADN was reduced in PS compared to control in an AMPK-independent fashion, suggesting the occurrence of novel mechanisms by which reduced cardiac ADN levels may regionally mediate the decline of cardiac function.