Effect of tea polyphenols on the contractile function of the papillary muscles of right ventricle in diabetic rats

AIM: To investigate the effect of tea polyphenols (TP) on the contractile function of the papillary muscles of right ventricle in the sixth and eighth week diabetic rats and the control rats. METHODS: Rats were induced to diabetic by an intravenous injection of alloxan. The papillary muscles of right ventricle in the sixth and eighth week diabetic rats were segregated and superfused with oxygenated Tyrode's solution. The contractile function and functional change under the electric stimulation state was recorded and compared between diabetic group and control group. RESULTS: 1/2 diastole interval elongation (P<0.05) and the depression of +dT/dtmax (P<0.01) and -dT/dtmax (P<0.05) of the papillary muscles of right ventricle were showed in the 6th week diabetic rats, while further damages, such as tension addition (P<0.01), 1/2 diastole interval elongation (P<0.01) and the depression of +dT/dtmax (P<0.01) and -dT/dtmax (P<0.01) in 8th week diabetic rats were also observed. TP at certain concentrations (15-120 mg/L) did not produce any effect on the 8th week diabetic rat's papillary muscle, but the positive muscle strength has been showed in the control rats and the sixth week diabetic rats. CONCLUSIONS: TP produces the positive muscle strength in the early diabetic cardiomyopathy, but has no beneficial effect on serious impaired diabetic myocardium.