Abstract: Objective To investigate the effects and mechanism of adenosine(ADO)on lipopolysaccharide(LPS)-induced neonatal rat cardiomyocyte hypertrophy.Methods The hypertrophy of primary cardiac cells of neonatal rat was induced by 1 mg/L LPS and the effect of different concentrations of adenosine on cardiac hypertrophy was observed.The size of cardiomyocytes was measured wtih a computer photograph analysis system and the expression of atrial natriuretic peptide mRNA was determined by reverse transcription PCR.Toll like receptor 4(TLR4)and tumor necrosis factor-α(TNF-α)were determined with western blot and enzyme-linked immunosorbent assay.Results Adenosine inhibited lipopolysaccharide-induced cardiac hypertrophy,with the decreased volume of 15.6%,27.1%,and 32.8% for low,moderate,and high ADO treament compared with that of model group(P<0.05 for all).The expression of atrial natriuretic peptide mRNA also decreased(P<0.01).ADO treatment abolished the inflammatory response induced by LPS,which was partially via attenuating TLR 4 signal pathway(P<0.05).The TNF-α decreased obviously by 56.3%,67.8%,and 72.9% at ADO doses of 0.25,1.00,and 4.00 mg/L(P<0.01 for all).ConclusionAdenosine has a protective effect on LPS-induced cardiac hypertrophy.The mechanism may be related to the inhibition of TLR 4.