Differential time course of liver and kidney glucose-6 phosphatase activity during fasting in rats.
We have studied the time course of hepatic and renal microsomal glucose-6 phosphatase (Glc-6Pase) during long-term fasting in the rat. Liver microsomal Glc-6Pase increases up to 48 hr and significantly decreases after 48 hr of fasting. The following activities were determined at 0, 24, 48, 72 and 96 hr: 0.31 +/- 0.02; 0.50 +/- 0.02; 0.54 +/- 0.03; 0.44 +/- 0.03; 0.44 +/- 0.01 mumol min-1 mg protein-1, respectively (all values are means +/- SEM, n = 6). Concomitantly, kidney microsomal Glc-6Pase progressively increases throughout the fast (Vm = 0.21 +/- 0.01; 0.26 +/- 0.004; 0.30 +/- 0.01; 0.37 +/- 0.02; 0.40 +/- 0.01 mumol min-1 mg protein-1, from 0 to 96 hr, respectively). These data suggest that the differential expression of Glc-6Pase activity in the liver and the kidney during long-term fasting could have an important role in the shift from a principally hepatic gluconeogenesis to a hepatic and renal gluconeogenesis.
Minassian
C
C
Institut National de la Santé et de la Recherche Médicale, Unit 197, Faculty of Medicine Alexis Carrel, Lyon, France.
Mithieux
G
G
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001835:Body Weight; D005215:Fasting; D019298:Glucose-6-Phosphate; D005958:Glucosephosphates / Q000378:metabolism*; D007668:Kidney / Q000201:enzymology* / Q000473:pathology; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology*; D009929:Organ Size; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
D001786:Blood Glucose; D005958:Glucosephosphates; D019298:Glucose-6-Phosphate