The role of pulmocutaneous baroreceptors in the control of lymphatic heartrate in the toad Bufo marinus

The influence of increased pulmocutaneous arterial systolic pressure on amp hibian lymph heart activity was determined in Bufo marinus. Arginine vasoto cin-induced increases in systolic arterial pressure of greater than 0.5 kPa significantly (P < 0.0002) decreased lymph heart rate. Denervation of the recurrent laryngeal nerve led to an increase in arterial pressure of 3.88 k Pa in test animals compared to control animals. Denervation abolished lymph heart response to increased arterial pressure for an average of 38 min. Di rect stimulation to the recurrent laryngeal nerve stopped lymph heart activ ity without an increase in arterial pressure. These data indicate that baro receptors in the pulmocutaneous artery can decrease lymph heart rate during periods of either direct stimulation or elevated arterial pressure. The da ta also support lymph hearts as effecters for aortic and carotid barorecept ors.