Fig. 7.

Average differential cutaneous (sympath. left ear), cardiac (right card. sympath.) and visceral (N. splanchn.) sympathetic activities (shown as percent changes, relative to average pre-stimulation activities, after analog integration of sympathetic discharges) in rabbits after sino-aortic denervation and vagotomy to eliminate peripheral chemoreceptors and arterial baroreceptors. Animals (two series with n = 6) were anesthetized and artificially ventilated under neuromuscular blockade. Shown are changes of regional sympathetic activities in response to ventilation with 10 % CO₂ in 21 % oxygen and 69 % nitrogen (black bars). The differential sympathetic response pattern during hypercapnia is qualitatively identical with those during asphyxia or arterial hypoxia. Its induction must be attributed to medullary CO₂ or pH chemoreceptors. Further shown are ear skin temperature (T _{left ear}) and heart rate (HR) which change according to the changes of regional sympathetic innervation. Mean arterial pressure (Pm _ar) rises during hypercapnia. From Simon and Riedel [76]