Involvement of an NAD(P)H oxidase as a pO2 sensor protein in the rat carotid body

• Published in: Biochemical journal Vol. 272; no. 3; pp. 743 - 747
• Main Authors: CROSS, A. R, HENDERSON, L, JONES, O. T. G, DELPIANO, M. A, HENTSCHEL, J, ACKER, H
• Format: Journal Article
• Language: English
• Published: Colchester Portland Press 15-12-1990
• Subjects: Analytical, structural and metabolic biochemistry; Animals; Biological and medical sciences; Carotid Body - cytology; Carotid Body - enzymology; Carotid Body - physiology; Chemoreceptor Cells - physiology; Cytochrome b Group - isolation & purification; Cytochrome b Group - metabolism; Enzymes and enzyme inhibitors; Flavin-Adenine Dinucleotide - analysis; Fluorescent Dyes; Fundamental and applied biological sciences. Psychology; NAD - analysis; NADH, NADPH Oxidoreductases - metabolism; NADP - analysis; NADPH Oxidases; Oxidoreductases; Oxygen - analysis; Rats; Rhodamine 123; Rhodamines; Spectrophotometry; Rat; Enzyme; Rodentia; Fluorescence; Chemoreceptor; Proteins; Absorption spectrometry; Vertebrata; Optical microscopy; Mammalia; Cytochrome b; Biosensor; Carotid body; Oxygen pressure; Photometry; Hydrogen peroxides
• ISSN: 0264-6021; 1470-8728
• DOI: 10.1042/bj2720743

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.