Oxalate synthesis from hydroxypyruvate in vitamin-B6-deficient rats.
We studied the effects of an intravenous hydroxypyruvate load on endogenous oxalogenesis in rats receiving a standard diet or a vitamin-B6-deficient diet. Twelve male Wistar rats were randomized to two groups and were fed either a standard diet or a vitamin-B6-deficient diet for 3 weeks. Then the animals received an intravenous infusion of 100 mg/ml (960.6 micromol/ml) of hydroxypyruvate slowly over 10 min. Urine samples were collected just before hydroxypyruvate infusion and at hourly intervals until 5 h afterward. Urinary oxalate, glycolate, and citrate levels were measured by capillary electrophoresis. Hourly urinary oxalate excretion peaked within 2 h, while urinary glycolate excretion peaked at 1 h, after the hydroxypyruvate load in both control and vitamin-B6-deficient rats. Both urinary oxalate and glycolate excretion were higher in vitamin-B6-deficient rats than in control rats. Infusion of hydroxypyruvate increased the 5-h urinary oxalate and glycolate excretion to 0.68% (6.56 micromol) and 0.53% (5.10 micromol) of the administered dose (mol/mol), respectively, in the control rats, while oxalate and glycolate excretion, respectively, increased to 2.43% (23.36 micromol) and 0.79% (7.59 micromol) of the dose in the vitamin-B6-deficient rats. Urinary citrate excretion was significantly lower at baseline and all other times in the vitamin-B6-deficient rats than in the control rats. In conclusion, a hydroxypyruvate load increased endogenous oxalate synthesis in control rats, and its synthesis was even greater in vitamin-B6-deficient rats. Vitamin B6 deficiency also resulted in significant hypocitraturia.
Teerajetgul
Yaovalak
Y
Division of Urology, Department of Organ-oriented Medicine, Faculty of Medicine, University of the Ryukyus, 207 Uehara, Nishihara, Okinawa 903-0215, Japan.
Hossain
Rayhan Zubair
RZ
Yamakawa
Kenichi
K
Morozumi
Makoto
M
Sugaya
Kimio
K
Ogawa
Yoshihide
Y
D000818:Animals; D019343:Citric Acid / Q000652:urine*; D006016:Glycolates / Q000652:urine*; D008297:Male; D010070:Oxalates / Q000652:urine*; D011773:Pyruvates / Q000378:metabolism*; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D052878:Urolithiasis / Q000378:metabolism; D026681:Vitamin B 6 Deficiency / Q000378:metabolism*
D006016:Glycolates; D010070:Oxalates; D011773:Pyruvates; C031149:glycolic acid; D019343:Citric Acid; C012375:hydroxypyruvic acid