Oxygen sensing in the carotid body.

In the present article we review in a concise manner the literature on the mechanisms of O2 chemoreception in the carotid body of adult mammals. In the first section we describe the basic structure of the carotid body, and define this organ as a secondary sensory receptor. In the second section is presented the most relevant literature on the O2 metabolism in the carotid body to define the parameters of O2 chemoreception, including hypoxic thresholds and P50 of the hypoxic responses. The final section is devoted to the mechanisms of detection of the hypoxic stimulus. We provide the data in favor and against each of the current three models on O2 chemoreception: the membrane model, the metabolic hypothesis with its different versions and the NAD(P)H oxidase model.