beta,gamma-Methylene ATP but not alpha,beta-methylene ATP mimics the inhibitory effect of ATP on ventricular automaticity

The effects of alpha,beta- and beta,gamma-methylene ATP on ventricular auto maticity induced by local injury in the right ventricle of rats pretreated with reserpine, were investigated and compared with the effects of ATP and adenosine. beta,gamma-Methylene ATP but not alpha,beta-methylene ATP mimick ed the inhibitory effect of both ATP and adenosine on the spontaneous autom aticity. In low concentrations, adenosine was more effective than ATP. alph a,beta-Methylene ATP caused little or no effect on ventricular automaticity . The results suggest that the effect of ATP might depend on its hydrolysis into AMP/adenosine.