Comparison of aortic and carotid chemoreceptor responses to hypercapnia and hypoxia

Abstract
A quantitative comparison of the responses between aortic and carotid chemoreceptors to steady-state levels of arterial CO2 and O2 partial pressure was made in 35 cats anesthetized, paralyzed and artificially ventilated. The measurements on the 2 receptors were made simultaneously in 6 cats and separately in 29 cats. The response of aortic chemoreceptors to a CO2 stimulus was a fraction of that of carotid chemoreceptors and the response to hypoxia was relatively blunted. The differences between the 2 chemoreceptors are quantitative rather than qualitative. Since a low arterial CO2 partial pressure stimulus attenuates the hypoxic response of carotid chemoreceptors, the low CO2 response of aortic body chemoreceptors may be responsible for their blunted hypoxic response.