title: Changes in pathways of pentose phosphate formation in relation to phosphoribosyl pyrophosphate synthesis in the developing rat kidney. Effects of glucose concentration and electron acceptors.
abstract: Phosphoribosyl pyrophosphate (PPRibP), required in nucleotide synthesis, increases 2-fold in rat kidney from 1 day post partum to adult stage; there is no accompanying increase in PPRibP synthetase activity measured in vitro. Ribose 5-phosphate is a key factor in the regulation of PPRibP synthesis. The activity and regulation of 3 routes of ribose 5-phosphate formation have been measured in renal growth: (i) the flux through the oxidative pentose phosphate pathway was high in the neonatal period but increased only +50% thereafter; (ii) the non-oxidative pentose phosphate pathway, including transketolase, increased by +145%; (iii) the rate-limiting enzymes of the glucuronate-xylulose route increased +200% from 1 day to the adult stage. The importance of systems reoxidizing NADPH was shown by: (i) the stimulation of renal PPRibP formation from glucose by phenazine methosulphate; (ii) the early involvement of the oxidative pentose phosphate pathway at the stage where NADPH is used for biosynthetic routes; (iii) the increasing involvement of the glucuronate-xylulose route, which acts as a transhydrogenase producing NADP+ in addition to pentose phosphate formation and (iv) the correlation between renal PPRibP content and the activity of aldose reductase, which, by utilization of NADPH, stimulates ribose 5-phosphate formation via the oxidative pentose phosphate pathway. Evidence is adduced that the contribution of the 3 routes of ribose 5-phosphate formation in the kidney varies at different stages of development.
authors: Department of Biochemistry, University College and Middlesex School of Medicine, London, U.K.
authors: M
authors: M
authors: Sochor
authors: S
authors: S
authors: Kunjara
authors: A L
authors: AL
authors: Greenbaum
authors: P
authors: P
authors: McLean
mesh_terms: D000818:Animals; D005260:Female; D005947:Glucose / Q000378:metabolism*; D005965:Glucuronates / Q000378:metabolism; D020723:Glucuronic Acid; D007668:Kidney / Q000254:growth & development* / Q000378:metabolism; D008297:Male; D010427:Pentose Phosphate Pathway / Q000187:drug effects; D010428:Pentosephosphates / Q000096:biosynthesis*; D010754:Phosphoribosyl Pyrophosphate / Q000096:biosynthesis*; D051381:Rats; D011919:Rats, Inbred Strains; D012268:Ribose-Phosphate Pyrophosphokinase / Q000378:metabolism; D014996:Xylulose / Q000378:metabolism
chemical_list: D005965:Glucuronates; D010428:Pentosephosphates; D014996:Xylulose; D010754:Phosphoribosyl Pyrophosphate; D020723:Glucuronic Acid; D012268:Ribose-Phosphate Pyrophosphokinase; D005947:Glucose