The rat carotid body tissue reveals a photometrically measurable haem signal with absorbance maxima at 560 nm, 518 nm and 425 nm, suggesting the presence of a b-type cytochrome; this was confirmed by pyridine haemochrome and CO spectra. The quantity of cytochrome b was estimated to be 310 pmol.mg of protein-1. This haem is capable of H2O2 formation, which can be inhibited by 10 microM-diphenyliodonium (DPI). The hypoxia-induced increase in nervous chemoreceptor discharge and the reduction of FAD and NAD(P)+ were also inhibited by DPI (10 microM). These results suggest that an oxidase such as the NAD(P)H oxidase of neutrophils may act as a pO2 sensor protein in the rat carotid body, probably inducing the pO2 chemoreceptor process by H2O2 formation.
Involvement of an NAD(P)H oxidase as a pO2 sensor protein in the rat carotid body
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A R Cross, L Henderson, O T G Jones, M A Delpiano, J Hentschel, H Acker; Involvement of an NAD(P)H oxidase as a pO2 sensor protein in the rat carotid body. Biochem J 15 December 1990; 272 (3): 743–747. doi: https://doi.org/10.1042/bj2720743
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