Cytochrome P450 3A, NADPH cytochrome P450 reductase and cytochrome b5 in the upper airways in horse.
Gene and protein expression as well as catalytic activity of cytochrome P450 (CYP) 3A were studied in the nasal olfactory and respiratory mucosa and the tracheal mucosa of the horse. We also examined the activity of NADPH cytochrome P450 reductase (NADPH P450 reductase), the amount of cytochrome b(5) and the total CYP content in these tissues. Comparative values for the above were obtained using liver as a control. The CYP3A related catalytic activity in the tissues of the upper airways was considerably higher than in the liver. The CYP3A gene and protein expression, on the other hand, was higher in the liver than in the upper airway tissues. Thus, the pattern of CYP3A metabolic activity does not correlate with the CYP3A gene and protein expression. Our results showed that the activity of NADPH P450 reductase and the level of cytochrome b(5) in the relation to the gene and protein expression of CYP3A were higher in the tissues of the upper airways than in the liver. It is concluded that CYP3A related metabolism in horse is not solely dependent on the expression of the enzyme but also on adequate levels of NADPH P450 reductase and cytochrome b(5).
Tydén
E
E
Department of Biomedical Sciences and Veterinary Public Health, Division of Pathology, Pharmacology and Toxicology, Swedish University of Agricultural Sciences, Box 7028, Uppsala, S-750 07, Sweden. Eva.Tyden@bvf.slu.se
Olsén
L
L
Tallkvist
J
J
Tjälve
H
H
Larsson
P
P
D000818:Animals; D051544:Cytochrome P-450 CYP3A / Q000235:genetics / Q000378:metabolism*; D015786:Cytochromes b5 / Q000235:genetics / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology; D006736:Horses / Q000378:metabolism*; D008099:Liver / Q000378:metabolism; D008297:Male; D009251:NADPH-Ferrihemoprotein Reductase / Q000235:genetics / Q000378:metabolism*; D009297:Nasal Mucosa / Q000378:metabolism; D020545:Respiratory Mucosa / Q000378:metabolism*; D014132:Trachea / Q000378:metabolism
D015786:Cytochromes b5; D051544:Cytochrome P-450 CYP3A; D009251:NADPH-Ferrihemoprotein Reductase