Regeneration of barosensitivity in the aortic nerve of cats when severed and transposed on various vessels in the neck.

1. In cats, regeneration of baroreceptors was studied in the aortic nerve after its peripheral end had been severed and sutured into an adventitial pouch of the common carotid artery (ten cats) on the wall of the external jugular vein (two cats) and into a cervical muscle (one cat). 2. Three weeks to four months after the initial operation, typical pulse synchronous baroreceptor activity was found in the whole desheathed nerve remnant in three of thirteen animals. This activity could be abolished by section of the vago-sympathetic bundle distal to the implantation site. 3. In every cat, including the one with the nerve in cervical muscle, bursts of spikes could be repeatedly evoked in the whole nerve upon stroking or distortion of the neuroma formed at the site of implantation. 4. Additionally, single barosensitive fibres could be teased from the aortic nerves in seven of the ten cats whose nerves has been sutured into the arterial wall. 5. Finally, distension sensitive single afferents with predominantly phasic response characteristics were found in the nerves on jugular veins. 6. Transposed aortic nerves therefore, are apparently capable of reinnervating the originally severed endings in some cases while forming a mechanosensitive neuroma in every case. When in contact with a vessel wall some truly barosensitive endings can also develop which in most instances have a more phasic than tonic response to pressure changes.