Absence of Chronotropic Effects of Dibutyryl Cyclic Adenosine 3', 5'-Monophosphate on the Dog S-A Node

Abstract

The in situ perfusion of the sinus node artery in six dogs was performed under constant pressure of 100mm Hg. Adenosine, cyclic AMP and dibutyryl cyclic AMP were administered into the sinus node artery. Adenosine at doses of 1 to 10 μg always induced marked negative chronotropic response. On the other hand, not only cyclic AMP, 100 μg to 1mg, but also dibutyryl cyclic AMP never induced any chronotropic response.