Central chemosensitivity to H+ and CO2 in the rat respiratory center in vitro.

The brainstem, cervical cord and attached phrenic nerve were excised from newborn rats and superfused in vitro. Respiratory output was measured by integration of phrenic nerve discharges. Respiratory output was enhanced by an increase in pCO2 at constant pH as well as by decreased pH with constant pCO2. It is concluded that the adequate stimulus to central chemoreceptors is not restricted only to H+.