title: Early renal brush border membrane adaptation to dietary phosphorus.
abstract: The present study evaluated uptake of phosphate by brush border membrane vesicles (BBMV) and alkaline phosphatase activities in brush border membrane fractions in rats fed a normal (0.6%) or low (0.03%) phosphorus diet for 24 h. After 2 min of incubation, the phosphate uptake by BBMV from rats ingesting normal and low phosphorus diets was 1,531 +/- 98 and 2,112 +/- 183 pmol/mg protein, respectively (p less than 0.025); peak glucose uptake was 226 +/- 17 and 209 +/- 42 pmol/mg protein, respectively. Vmax increased 74% in the 0.03% dietary phosphorus groups (p less than 0.005) while Km was similar between groups. Alkaline phosphatase activities were 824 +/- 48 and 816 +/- 56 nmol/min/mg protein with the respective diets. The earliest detectable increase in phosphate uptake by BBMV occurred within 4 h of dietary phosphorus deprivation while alkaline phosphatase increased 3 days later. Renal adaptation to phosphate deprivation can occur within 4 h, is not due solely to a change in the filtered load of phosphate and occurs before increases in the specific activity of alkaline phosphatase.
mesh_terms: D000222:Adaptation, Physiological; D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D004032:Diet; D005947:Glucose / Q000378:metabolism; D007672:Kidney Cortex / Q000378:metabolism* / Q000648:ultrastructure; D008297:Male; D008871:Microvilli / Q000201:enzymology / Q000378:metabolism*; D010710:Phosphates / Q000097:blood / Q000652:urine; D010758:Phosphorus / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D000520:alpha-Glucosidases / Q000378:metabolism
chemical_list: D010710:Phosphates; D010758:Phosphorus; D000469:Alkaline Phosphatase; D000520:alpha-Glucosidases; D005947:Glucose