An adenosine A1 agonist 2-chloro-N6 cyclopentyladenosine inhibits the angiotensin II-induced cardiomyocyte hypertrophy through the calcineurin pathway.

OBJECTIVES

The aim of this investigation was to study the underlying mechanism of an adenosine A1 receptor agonist 2-chloro-N6 cyclopentyladenosine (CCPA) inhibiting cardiomyocyte hypertrophy induced by angiotensin II (AngII).

METHODS

Neonatal rat cardiomyocytes were treated with AngII to generate a cardiomyocyte hypertrophy model. Cardiomyocyte cultures were randomized into 5 groups: control; AngII; AngII + cyclosporin A (CsA); AngII + CCPA, and AngII + CCPA + DPCPX. Cardiomyocyte viability was measured by MTT assay. Protein synthesis was assessed by the application of (3)H leucine ((3)H-Leu) incorporation into protein. The mRNA expressions of atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP), β-myosin heavy chain (β-MHC) and calcineurin Aβ (CnAβ) were measured by real-time quantitative PCR. The protein level of CnAβ was dissected by Western blotting.

RESULTS

AngII administration at lower concentrations increased the cardiomyocytes viabilities gradually. Surface area, mRNA expressions of ANP, BNP and β-MHC, and (3)H-Leu incorporation of AngII-induced cardiomyocytes were increased in a dose-dependent manner. As a calcineurin-specific inhibitor, CsA inhibited (3)H-Leu incorporation, surface area, mRNA expressions of ANP, BNP, β-MHC, CnAβ and protein expression of CnAβ of AngII-induced cardiomyocytes. CCPA also suppressed the mRNA and protein expressions of CnAβ and exerted antihypertrophic effects to a greater degree than CsA. The inhibition of CCPA on cardiomyocyte hypertrophy was counteracted by the A1 receptor antagonist DPCPX.

CONCLUSION

The A1 receptor agonist CCPA could significantly inhibit AngII-induced cardiomyocyte hypertrophy via the calcineurin signaling pathway.