Excitation of afferent fibres in the cardiac sympathetic nerves induced by coronary occlusion and injection of bradykinin. The influence of acetylsalicylic acid and dipyron.

Afferent impulse activity was recorded in single fibres of the inferior cardiac sympathetic nerve of the cat. When the descending branch of the left coronary artery was ligated for 60 sec an enhancement of afferent impulses was recorded. Elevations in discharge frequency were also induced by injecting bradykinin, epinephrine, and isoprenaline or by general hypoxia due to interruption of the artificial ventilation. When these procedures were after pretreatment with the analgesic agents, acetylsalicylic acid or dipyron a reduction in spike discharge was observed only with bradykinin after application of acetylsalicylic acid. No influence of these pretreatments on the effects of coronary occlusion, general hypoxia and injection of epinephrine and isoprenaline could be observed. These results suggest that bradykinin does not predominate as mediator substance in eliciting ischemic heart pain.