Phrenic nerve afterdischarge after electrical stimulation of the carotid sinus nerve in cats

The phrenic nerve afterdischarge in cats after electrical stimulation of the carotid sinus nerve (CSN) at different levels of PETCO2, PETO2 and anaesthesia, both with vagi intact and cut, is fitted to a mono-exponential decay. It is concluded that the time constant of this decay is not influenced by blood gas values, anaesthesia and vagotomy. However, the magnitude of the afterdischarge tends to zero at higher levels of phrenic nerve activity, so the phenomenon disappears. The results are explained by restricted central phasic sensitivity and the consequences for respiration control are discussed.