Antagonistic influences of dibutyryl cyclic AMP and dibutyryl cyclic GMP on the beating rate of cultured mouse myocardial cells.

Cultured myocardial cells obtained from neonatal mouse ventricles beat spontaneously and rhythmically. Norepinephrine and dibutyryl cyclic AMP accelerated the rate of spontaneous beating. Dibutyryl cyclic GMP slightly decreased the rate of spontaneous beating. The acceleration of the beating rate of cultured myocardial cells by norepinephrine or dibutyryl cyclic AMP was counteracted by dibutyryl cyclic GMP. Preincubation of cultured myocardial cells with dibutyryl cyclic GMP prevented the positive chronotropic effect of dibutyryl cyclic AMP.