Cytochrome P-450 4A isoform expression and 20-HETE synthesis in renal preglomerular arteries.
20-Hydroxyeicosatetraenoic acid (20-HETE), a potent vasoconstrictor and mediator of the myogenic response, is a major arachidonic acid metabolite in the microvasculature of the rat kidney formed primarily by the cytochrome P-450 (CYP) 4A isoforms, CYP4A1, CYP4A2, and CYP4A3. We examined CYP4A isoform expression and 20-HETE synthesis in microdissected interlobar, arcuate, and interlobular arteries; mRNA for all CYP4A isoforms was identified by RT-PCR. Western blot analysis indicated that the levels of CYP4A2/4A3-immunoreactive protein increased with decreased arterial diameter, whereas those of CYP4A1-immunoreactive protein remained unchanged. 20-HETE synthesis was the highest in the interlobular arteries (17 +/- 1.62 nmol. mg(-1). h(-1)) and, like CYP4A2/4A3-immunoreactive protein, decreased with increasing vessel diameter (4.5 +/- 1.21, 2.65 +/- 0.58, and 0.81 +/- 0.14 nmol. mg(-1). h(-1) in the arcuate, interlobar, and segmental arteries, respectively). 20-HETE synthesis in the renal artery and the abdominal aorta was undetectable. The observed decreased immunoreactivity of NADPH-cytochrome P-450 (c) oxidoreductase with increased arterial diameter provided a possible explanation for the decreased capacity to generate 20-HETE in the large arteries. The increase in CYP4A isoform expression and 20-HETE synthesis with decreasing diameter along the preglomerular arteries and the potent biological activity of 20-HETE underscore the significance of 20-HETE as a modulator of renal hemodynamics.
Marji
Jackleen S
JS
Department of Pharmacology, New York Medical College, Valhalla, New York 10595, USA.
Wang
Mong-Heng
MH
Laniado-Schwartzman
Michal
M
D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D042926:Cytochrome P-450 CYP4A; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics*; D015971:Gene Expression Regulation, Enzymologic; D006893:Hydroxyeicosatetraenoic Acids / Q000096:biosynthesis*; D007678:Kidney Glomerulus / Q000098:blood supply*; D008297:Male; D008833:Microcirculation / Q000502:physiology; D006899:Mixed Function Oxygenases / Q000235:genetics*; D009251:NADPH-Ferrihemoprotein Reductase / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012077:Renal Artery / Q000378:metabolism*; D014661:Vasoconstriction / Q000502:physiology
D006893:Hydroxyeicosatetraenoic Acids; D016718:Arachidonic Acid; C055987:20-hydroxy-5,8,11,14-eicosatetraenoic acid; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D042926:Cytochrome P-450 CYP4A; D009251:NADPH-Ferrihemoprotein Reductase