What is the clinical evidence from this study?

Study design: Other. Population: Cardiac hypertrophy and heart failure. Intervention: 2-chloroadenosine (CADO) and N6-cyclopentyladenosine (CPA) vs. Untreated TAC group. Primary outcome: Heart to body weight ratio (mg/g) (p=<0.0001).

September 16, 2003Open Access

Activation of Adenosine A 1 Receptor Attenuates Cardiac Hypertrophy and Prevents Heart Failure in Murine Left Ventricular Pressure-Overload Model

Q: What are the key findings of this study?

Treatment with the adenosine analogue CADO significantly reduced heart to body weight ratio (6.80 vs 8.34 mg/g, P<0.0001) in mice with pressure-overload hypertrophy.

Key Result

Treatment with the adenosine analogue CADO significantly reduced heart to body weight ratio (6.80 vs 8.34 mg/g, P<0.0001) in mice with pressure-overload hypertrophy.

Structured PICO

Does activation of adenosine A1 receptors attenuate cardiac hypertrophy and prevent heart failure in murine left ventricular pressure-overload models?

Population

In vitro neonatal rat cardiomyocytes and in vivo C57BL/6 male mice subjected to transverse aortic constriction to induce cardiac hypertrophy.

Intervention

2-chloroadenosine (CADO) or selective adenosine A1 agonist N6-cyclopentyladenosine (CPA)

Comparator

Transverse aortic constriction (TAC) without treatment

Outcome

Heart to body weight ratio and lung to body weight ratiosurrogate

Activation of adenosine A1 receptors attenuates cardiac hypertrophy and myocardial dysfunction in a murine pressure-overload model.

Main Result

Absolute Event Rate: 6.8% vs 8.34%

p-value: p=<0.0001

Abstract

Sympathomimetic stimulation, angiotensin II, or endothelin-1 is considered to be an essential stimulus mediating ventricular hypertrophy. Adenosine is known to protect the heart from excessive catecholamine exposure, reduce production of endothelin-1, and attenuate the activation of the renin-angiotensin system. These findings suggest that adenosine may also attenuate myocardial hypertrophy. To verify this hypothesis, we examined whether activation of adenosine receptors can attenuate cardiac hypertrophy and reduce the risk of heart failure. Our in vitro study of neonatal rat cardiomyocytes showed that 2-chloroadenosine (CADO), a stable adenosine analogue, inhibits protein synthesis of cardiomyocytes induced by phenylephrine, endothelin-1, angiotensin II, or isoproterenol, which were mimicked by the stimulation of adenosine A1 receptors. For our in vivo study, cardiac hypertrophy was induced by transverse aortic constriction (TAC) in C57BL/6 male mice. Four weeks after TAC, both heart to body weight ratio (6.80+/-0.18 versus 8.34+/-0.33 mg/g, P<0.0001) as well as lung to body weight ratio (6.23+/-0.27 versus 10.03+/-0.85 mg/g, P<0.0001) became significantly lower in CADO-treated mice than in the TAC group. Left ventricular fractional shortening and left ventricular dP/dtmax were improved significantly by CADO treatment. Similar results were obtained using the selective adenosine A1 agonist N6-cyclopentyladenosine (CPA). A nonselective adenosine antagonist, 8-(p-sulfophenyl)-theophylline, and a selective adenosine A1 antagonist, 8-cyclopentyl-1,3-dipropylxanthine, eliminated the antihypertrophic effect of CADO and CPA, respectively. The plasma norepinephrine level was decreased and myocardial expression of regulator of G protein signaling 4 was upregulated in CADO-treated mice. These results indicate that the stimulation of adenosine receptors attenuates both the cardiac hypertrophy and myocardial dysfunction via adenosine A1 receptor-mediated mechanisms.