Regulation of P-450 4A activity in the glomerulus of the rat.
We recently reported that an enzyme of the cytochrome P-450 4A family is expressed in the glomerulus, but there is no evidence that 20-hydroxyeicosatetraenoic acid (20-HETE) can be produced by this tissue. The purpose of present study was to determine whether glomeruli isolated from the kidney of rats can produce 20-HETE and whether the production of this metabolite is regulated by nitric oxide (NO) and dietary salt intake. Isolated glomeruli produced 20-HETE, dihydroxyeicosatrienoic acids, and 12-hydroxyeicosatetraenoic acid (4.13 +/- 0.38, 4.20 +/- 0.38, and 2. 10 +/- 0.20 pmol. min-1. mg protein-1, respectively) when incubated with arachidonic acid (10 microM). The formation of 20-HETE was dependent on the availability of NADPH and the PO2 of the incubation medium. The formation of 20-HETE was inhibited by NO donors in a concentration-dependent manner. The production of 20-HETE was greater in glomeruli isolated from the kidneys of rats fed a low-salt diet than in kidneys of rats fed a high-salt diet (5.67 +/- 0.32 vs. 2.83 +/- 0.32 pmol. min-1. mg protein-1). Immunoblot experiments indicated that the expression of P-450 4A protein in glomeruli from the kidneys of rats fed a low-salt diet was sixfold higher than in kidneys of rats fed a high-salt diet. These results indicate that arachidonic acid is primarily metabolized to 20-HETE and dihydroxyeicosatrienoic acids in glomeruli and that glomerular P-450 activity is modulated by NO and dietary salt intake.
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Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA.
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D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid / Q000378:metabolism; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D042926:Cytochrome P-450 CYP4A; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004039:Diet, Sodium-Restricted; D006893:Hydroxyeicosatetraenoic Acids / Q000037:antagonists & inhibitors / Q000378:metabolism; D066298:In Vitro Techniques; D007678:Kidney Glomerulus / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D009249:NADP / Q000494:pharmacology; D020030:Nitric Oxide Donors / Q000494:pharmacology; D051381:Rats; D011917:Rats, Inbred Lew
D006893:Hydroxyeicosatetraenoic Acids; D020030:Nitric Oxide Donors; D016718:Arachidonic Acid; D009249:NADP; D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic 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