8-bromo cyclic gmp and n2-2'-o-'dibutyryl cyclic gmp , in concentrations of 4.2 to 8.4 - 10 ( -4 ) m , exerted only very slight depressant effects on the basal rate of beat , but strongly antagonized , and in the majority of experiments with 8-bromo cyclic gmp completely suppressed , the positive chronotropic action of adrenaline .
C1372804
positive chronotropic
C0014563
adrenaline