Role of endogenous CYP450 metabolites of arachidonic acid in maintaining the glomerular protein permeability barrier.
This study examined the metabolism of arachidonic acid (AA) by cytochrome P-450 enzymes in isolated glomeruli and the effects of selective inhibitors of the synthesis of 20-hydroxyeicosatetraenoic acid (20-HETE) and epoxyeicosatetraenoic acids (EETs) on glomerular permeability to albumin (P(alb)). Glomeruli avidly produced 20-HETE, EETs, dihydroxyeicosatetraenoic acids (diHETEs), and HETEs when incubated with exogenous AA. N-hydroxy-N'-(4-butyl-2-methylphenyl)formamidine (HET0016; 10 microM) selectively inhibited the formation of 20-HETE by 95% and increased P(alb) from 0.00 +/- 0.08 to 0.73 +/- 0.10 (n = 43 glomeruli, 4 rats). Addition of a 20-HETE mimetic, 20-hydroxyeicosa-5(Z),14(Z)-dienoic acid (20-5,14-HEDE; 1 microM) opposed the effects of HET0016 (10 microM) to increase P(alb) (0.21 +/- 0.10, n = 36 glomeruli, 4 rats). Preincubation of glomeruli with exogenous AA to increase basal production of 20-HETE had a similar effect. We also examined the effect of an epoxygenase inhibitor, N-methylsulfonyl-6-(2-propargyloxyphenyl)hexanamide (MSPPOH; 5 microM), on P(alb). MSPPOH (5 microM) significantly increased P(alb) but had no effect on the synthesis of EETs in glomeruli incubated with AA. However, MSPPOH (5 microM) selectively reduced epoxygenase activity by 50% in glomeruli incubated without added AA. Pretreatment with 8,9-EET (100 nM) attenuated the effects of MSPPOH (5 microM) on P(alb). These results indicate that glomeruli produce 20-HETE, EETs, diHETEs, and HETEs and that endogenously formed 20-HETE and EETs play an essential role in the maintenance of the glomerular permeability barrier to albumin.
Williams
Jan Michael
JM
Department of Physiology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
Sharma
Mukut
M
Anjaiahh
Siddam
S
Falck
John R
JR
Roman
Richard J
RJ
D000577:Amides / Q000378:metabolism; D000578:Amidines / Q000378:metabolism; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism*; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D006893:Hydroxyeicosatetraenoic Acids / Q000378:metabolism; D007678:Kidney Glomerulus / Q000378:metabolism*; D008297:Male; D010539:Permeability; D011506:Proteins / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
D000577:Amides; D000578:Amidines; C000708209:HET0016; D006893:Hydroxyeicosatetraenoic Acids; C121756:N-methylsulfonyl-6-(2-propargyloxyphenyl)hexanamide; D011506:Proteins; D016718:Arachidonic Acid; C055987:20-hydroxy-5,8,11,14-eicosatetraenoic acid; D003577:Cytochrome P-450 Enzyme System