The relationship of the vasomotor and respiratory regions in the medulla oblongata of the sheep

That the reticular formation of the medulla oblongata controls the respiratory and vasomotor systems has been established experimentally. Many investiga,ions have aimed at delimiting the medullary respiratory centres (Cordier & Heymans, 1935; Pitts, 1946), but fewer attempts have been made to define exactly medullary regions which influence vasomotor activity (Monnier, 1941; Alexander, 1946). The relationship of vasomotor and respiratory responses elicitable from the medulla oblongata by direct electrical stimulation has received little attention. Pitts, Magoun & Ranson (1939), in their study of respiratory centres in the cat, comment upon the independence of respiratory and vascular responses, since any locus which produced a respiratory response failed to show a simultaneous vasomotor response. This paper describes the results of experiments in which the medulla oblongata of sheep was explored systematically and both respiratory and vasomotor responses were recorded. The results show an anatomical relationship of the respiratory and vasomotor regions, but the function of the two systems appears to remain largely independent.