Pacinian Corpuscles in the Mesentery and Their Relation to the Vascular System. ∗

Abstract

The question has frequently been raised 1 , 2 as to whether there are vascular zones other than the carotid sinus and the aorta that make an afferent contribution to cardiovascular reflexes. A region that might well be suspect is the mesenteric area and we have accordingly investigated the problem of the afferent nerve discharge therefrom especially with relation to blood pressure.

As a means of approach impulses were recorded in the peripheral end of the splanchnic nerve or in its terminal branches which run along the mesenteric arteries. Characteristically there is a discharge of impulses synchronous with each pulse as in Fig. 1, although in certain cases there is a considerable amount of activity in the intervals between succeeding systoles. The general picture of this afferent discharge is similar to that observed 3 in the carotid sinus and aortic nerves.

The modifications effected in the discharge by variations in intravascular pressure are likewise similar to those found in the case of the carotid sinus and aorta although less constant and predictable. When a portion of the mesenteric artery is perfused at steady pressures it is found that the end organs begin to discharge at a certain minimal pressure, the impulse frequency and number of active end organs increasing with further increases in pressure. In the intact preparation the degree of discharge is largely influenced by the magnitude of the pulse pressure, its rate of change, and especially by the blood volume. An increase in the latter increases the frequency of the afferent impulses. An increase in mean blood pressure, especially if the previous pressure is not too high, also produces an increase in the discharge although in some cases an increase in blood pressure resulting from an injection of adrenalin gave an initial decrease in the number of impulses. This may be due to a change in the relation of the vessels to the end organs.