Respiratory responses to chemical activation of left ventricular receptors.

Respiratory responses to chemical activation of receptors in the left ventricle were measured in anesthetized cats. Application of capsaicin (10 micrograms) or bradykinin (500 ng) to the serosal surface of the left ventricle caused increases in phrenic nerve activity and in arterial pressure. These responses persisted after cervical vagotomy and after bilateral transection of the carotid sinus nerves. Bilateral stellate ganglionectomy abolished the respiratory responses to capsaicin and bradykinin. In addition, stellate ganglionectomy prevented the arterial pressure response to bradykinin; however, a slight increase in arterial pressure occurred with application of capsaicin. It is concluded that activation of sympathetic afferents originating in the left ventricle causes an increase in respiratory output.