A reflexogenic area for controlling the blood pressure in toad (Bufo vulgaris formosa)

In the toad, Bufo vulgaris, the pulmocutaneous artery, which is innervated by a fine branch of the laryngeal nerve, was shown to be a reflexogenic area affecting the systemic blood pressure. Distension of the vascularly isolated pulmocutaneous artery evoked falls in systemic blood pressure. Impulses in bursts, synchronous with the systolic rise of the blood pressure, were recorded from the peripheral cut end of the laryngeal nerve when all branches, save the one innervating the pulmocutaneous artery, had been divided. Differing from mammalian baroreceptors, those in toads occurred with a marked latency in response to rises in blood pressure. A hyperbolic relation was obtained between the pressure and the latency. Existence of these baroreceptors in pulmocutaneous artery was confirmed in preparations in vitro. Punctate stimulation was used to localize the baroreceptive site.