Phosphate transport in brush border membrane vesicles isolated from renal cortex of young growing and adult rats

1982 ◽  
Vol 394 (3) ◽  
pp. 217-221 ◽  
Author(s):  
J. Caverzasio ◽  
H. Murer ◽  
H. Fleisch ◽  
J. -P. Bonjour
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Renal Cortex ◽  
Membrane Vesicles ◽  
Phosphate Transport ◽  
Brush Border Membrane Vesicles ◽  
Adult Rats

The defect in transcellular transport of phosphate in the nephron is located in brush-border membranes in X-linked hypophosphatemia (Hyp mouse model)

1978 ◽  
Vol 56 (6) ◽  
pp. 640-646 ◽  
Author(s):  
H. S. Tenenhouse ◽  
C. R. Scriver
Keyword(s):  
Gene Product ◽  
Glucose Transport ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Renal Cortex ◽  
Membrane Vesicles ◽  
Mutant Gene ◽  
Phosphate Transport ◽  
Brush Border Membrane Vesicles ◽  
Brush Border Membranes

We purified renal cortex brush-border membranes from mutant hemizygous hypophosphatemic (Hyp/Y) mice and male control (+/Y) littermates. Tenfold purification of mutant and wild-type membranes was obtained. Phosphate enters +/Y brush-border membrane vesicles by a saturable Na+-dependent arsenate-inhibited component and also by a diffusional component observed in the presence of a potassium gradient. Phosphate is not bound or incorporated significantly by mouse brush-border membrane vesicles. Parallel studies with rat renal cortex brush-border membrane vesicles revealed that phosphate and D-glucose transport in rat and mouse vesicles are similar and have the characteristics reported by other workers. Brush-border membrane vesicles prepared from Hyp/Y renal cortex have significant (p < 0.001) partial loss of phosphate transport on the Na+-dependent arsenate-inhibited component. D-Glucose transport is not affected. Our previous studies reveal that other components of transcellular phosphate flux in kidney are normal. Therefore, we conclude that the mutant gene product in the Hyp mouse is confined to the brush-border membrane. Stability of the X-chromosome in mammalian evolution implies that the same gene product is involved in the classic human disease, familial 'vitamin D resistant' X-linked hypophosphatemia.

Effect of temperature and pH on phosphate transport through brush border membrane vesicles in rats

1984 ◽  
Vol 62 (2) ◽  
pp. 229-234 ◽  
Author(s):  
Michèle G. Brunette ◽  
Richard Beliveau ◽  
Meanthan Chan
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Phosphate Uptake ◽  
Membrane Vesicles ◽  
Phosphate Transport ◽  
Mean Value ◽  
Brush Border Membrane Vesicles ◽  
Effect Of Temperature ◽  
Total Phosphate ◽  
Renal Brush Border Membrane

The kinetics of sodium gradient dependent phosphate uptake by the renal brush border membrane vesicles of the rat have been studied under various conditions of temperature and pH. From 7 to 30 °C the Lineweaver-Burk plots are linear, and the apparent Km progressively increases from 54 to 91 μM. Above 30 °C, the apparent Km continues to increase to reach 135 μM at 40 °C, but a break is observed in the Lineweaver-Burk plots at the substrate concentration of 300 μM. The existence of this break, confirmed by the Eadie-Hofstee plot supports the hypothesis of a dual mechanism of phosphate transport, one for low concentrations of substrate with a Km of 100 μM and the other for high concentrations with a Km of approximately 240 μM. When the two components of the Eadie-Hofstee plot are analyzed according to a nonlinear regression program, these two values of Km become 70 μM and 1.18 mM, respectively. The Vmax continuously increases with temperature. However, the Arrhenius plot (In Vmax vs. 1/Tk) shows an abrupt discontinuity at 23 °C. pH experiments were performed at 35 °C. In the absence of a proton gradient, increasing the pH from 6.5 to 7.5 and 8.5 decreases the apparent Km from 341 to 167 and 94 μM, respectively. When only the divalent form of phosphate is considered as the substrate, the apparent Km does not vary anymore with the pH and remains around the mean value of 105 μM. The uniformity of the apparent Km for the total phosphate uptake, when only the divalent phosphate is considered as being the substrate, suggests that this divalent form is the only one which is transported. Whatever the substrate considered, total phosphate or divalent phosphate, the highest Vmax is obtained at pH 7.5 which probably approximates the optimum pH inside the vesicles for the phosphate uptake.

Effect of thyroxine administration on phosphate transport across renal cortical brush border membrane

1984 ◽  
Vol 246 (2) ◽  
pp. F133-F139 ◽  
Author(s):  
R. E. Espinosa ◽  
M. J. Keller ◽  
A. N. Yusufi ◽  
T. P. Dousa
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Renal Cortex ◽  
Membrane Vesicles ◽  
Phosphate Transport ◽  
Treated Group ◽  
Renal Tubular Reabsorption ◽  
Renal Tubular ◽  
And Control ◽  
Cortical Slices

Previous studies indicate that in hyperthyroid states the renal tubular reabsorption of phosphate is enhanced. To determine the cellular basis of this phenomenon, we investigated the effect of L-thyroxine (T4) administration on Pi transport across brush border membrane vesicles (BBMV) from rat renal cortex. Rats were thyroparathyroidectomized, fed a diet containing 1.2% phosphate, and treated intraperitoneally for 6 days with 200 micrograms T4 X 100 g body wt-1 X day-1. At the end of the treatment period, the rats had a significantly (+ delta 25%) elevated plasma Pi and a slightly decreased plasma Ca compared with controls. The renal clearance of Pi was not different between the two groups. Na+ gradient-dependent uptake of 32Pi by BBMV from renal cortex was significantly enhanced in T4-treated rats. BBMV uptake of 32Pi in the absence of Na+ -gradient as well as Na+ gradient-dependent uptake of D-[3H]glucose and L-[3H]proline did not differ between BBMV from T4-treated and control rats. Kinetic analysis showed that the Na+ gradient-dependent 32Pi transport system in BBMV from T4-treated rats had a significantly increased Vmax compared with controls (5.2 +/- 0.4 vs. 4.1 +/- 0.4 nmol Pi X 30 s-1 X mg protein-1) and also a slightly higher affinity for Pi (apparent Km in controls, 95 +/- 9; in T4-treated, 78 +/- 8 microM). Gluconeogenesis in cortical slices was not significantly different between T4-treated rats and controls. Specific activities of alkaline phosphatase and gamma-glutamyltransferase were significantly lower in BBMV from the T4-treated group compared with controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of Endothelin 1 on Phosphate Transport in Brush Border Membrane Vesicles

Nephron ◽  
1997 ◽  
Vol 76 (1) ◽  
pp. 72-76 ◽  
Author(s):  
Miki Shimada ◽  
Kiyoshi Hirano ◽  
Yasuhiko Tomino
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Phosphate Transport ◽  
Brush Border Membrane Vesicles ◽  
Endothelin 1
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