A role for cyclic GMP in the initiation of cardiac pressor reflexes by bradykinin and capsaicin.

Reflexogenic effects of bradykinin on the cardiac sympathetic afferents supplying the dog epicardium were inhibited by treatment of the heart surface with either methylene blue or the compound LY-83583 (6-anilino-5,8-quinolinedione), which are known to lower cellular levels of cyclic GMP. Stimulation of cyclic GMP production by epicardial treatment with the NO-containing synonimine compound, SIN-1, potentiated bradykinin-induced reflex effects. In contrast, the sympathetic cardiac pressor response induced by capsaicin was not influenced by epicardial treatment with either methylene blue, LY-83583 or SIN-1. These findings indicate the importance of cyclic GMP for the reflexogenic activity of bradykinin, but not that of capsaicin on the sympathetic afferents supplying the dog heart.