Integration of Central and Peripheral Respiratory Chemoreflexes

Abstract

A debate has raged since the discovery of central and peripheral respiratory chemoreceptors as to whether the reflexes they mediate combine in an additive (i.e., no interaction), hypoadditive or hyperadditive manner. Here we critically review pertinent literature related to O2 and CO2 sensing from the perspective of system integration and summarize many of the studies on which these seemingly opposing views are based. Despite the intensity and quality of this debate, we have yet to reach consensus, either within or between species. In reviewing this literature, we are struck by the merits of the approaches and preparations that have been brought to bear on this question. This suggests that either the nature of combination is not important to system responses, contrary to what has long been supposed, or that the nature of the combination is more malleable than previously assumed, changing depending on physiological state and/or respiratory requirement.

Acute intermittent hypoxia with concurrent hypercapnia evokes P2X and TRPV1 receptor‐dependent sensory long‐term facilitation in naïve carotid bodies

“…; Xing & Pilowsky ). These results are somewhat unexpected because hypercapnia might be expected to increase sympathetic LTF based on: (i) hypercapnia increasing the CB and ventilatory responses to hypoxia (Lahiri & Delaney, ; Wilson & Teppema, ) and (ii) Fletcher () and coworkers (Bao et al . ) showing that the addition of inspired CO 2 decreases the caused by inspired hypoxia and augments the effects of each hypoxic bout on sympathetic activity and blood pressure (Bao et al .…”

Advances in cellular and integrative control of oxygen homeostasis within the central nervous system

“…To mount an effective response to changes in blood gases, O 2 sensing mechanisms within the CNS must be tightly coordinated with inputs derived from peripheral chemosensory mechanisms (Basting et al . ; Wilson & Teppema, ; Guyenet et al . ).…”

CO2 retention: The key to stopping hiccups

“…There are two kinds of blood gas sensors in the human body . The central chemoreceptors, located in the medulla, detect high levels of CO 2 in the blood, while the carotid bodies detect low levels of O 2.…”