Reflex stimulation of aortic chemoreceptors and the role of vascular receptors.

Impulses were recorded in single afferent fibres of aortic chemoreceptors of cats anaesthetized with chloralose. As expected raising the blood pressure (BP) passively by occluding the abdominal aorta, consistently reduced or abolished the activity of the chemoreceptors. This reduction persisted for as long as the BP remained high. Stimulating the sensory receptors of the small intestines increased the activity of 10 aortic chemoreceptors. The increased activity persisted after bilateral adrenalectomy but it was abolished by blocking the nerves of the mesentery with xylocaine. The increased activity was noteworthy because it occurred in spite of the rise in blood pressure (that always occurred when the intestines were squeezed) which by itself would tend to reduce the activity of the chemoreceptors. It was concluded that stimulating the intestinal receptors produces a reflex increase in the activity of aortic chemoreceptors by causing a reduction of glomeral blood flow through impulses in the sympathetic fibres.