title: Localization and properties of NAD+-dependent 15-hydroxyprostaglandin dehydrogenase activity in the rat kidney.
abstract: Localization of NAD+-dependent (type I) 15-hydroxyprostaglandin dehydrogenase (15PGDH) in the rat kidney was examined using an ultramicro assay of the enzyme activity based on the enzymatic cycling method. The enzyme activities during first 3 weeks of age were 30- to 40-fold higher than the adult and rapidly decreased by 4th week. 15PGDH activities measured with either PGE2 or PGF2 alpha as a substrate were five times higher in slices from midcortical or juxtamedullary layers than in slices from the superficial cortex of 3 week-old rat kidney. Little activity was found in inner medulla and papilla. When the enzyme activity was assayed using isolated nephron segments dissected from collagenase treated slices of 3 week-old rat kidneys, the activity was localized only in the proximal convoluted and straight tubules with either PGs (PGE2: 1.75 +/- 0.25 in PCT, 7.70 +/- 1.19 in PST, and PGF2 alpha: 1.63 +/- 0.39, 6.18 +/- 1.52 pmoles NADH/mm/40 min). The kinetic analysis for renal 15PGDH of 3 week-old rats revealed that Km for PGE2 (8.4 microM) was lower than that for PGF2 alpha (22.6 microM) with constant NAD+, while Vmax for both was similar. In contrast, both Km and Vmax for NAD+ were identical with either PGs. These data suggest that the rate-limiting factor of type I 15PGDH is the concentration of prostaglandins in the kidney rather than the concentration of NAD+.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000375:Aging; D000818:Animals; D006911:Hydroxyprostaglandin Dehydrogenases / Q000145:classification / Q000378:metabolism*; D007668:Kidney / Q000201:enzymology*; D007700:Kinetics; D008297:Male; D009243:NAD / Q000502:physiology*; D009399:Nephrons / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors; D014018:Tissue Distribution
chemical_list: D011506:Proteins; D009243:NAD; D006911:Hydroxyprostaglandin Dehydrogenases; C035859:15-hydroxyprostaglandin dehydrogenase