Competitive, uncompetitive, and mixed inhibitors of the alkaline phosphatase activity associated with the isolated brush border membrane of the tapewormHymenolepis diminuta

1989 ◽  
Vol 40 (2) ◽  
pp. 239-248 ◽  
Author(s):  
Peter W. Pappas ◽  
David A. Leiby
Keyword(s):  
Alkaline Phosphatase ◽  
Phosphatase Activity ◽  
Alkaline Phosphatase Activity ◽  
Brush Border ◽  
Brush Border Membrane

scholarly journals Alkaline phosphatase activity does not mediate phosphate transport in the renal-cortical brush-border membrane

1980 ◽  
Vol 190 (2) ◽  
pp. 473-476 ◽  
Author(s):  
H S Tenenhouse ◽  
C R Scriver ◽  
E J Vizel
Keyword(s):  
Alkaline Phosphatase ◽  
Phosphatase Activity ◽  
Alkaline Phosphatase Activity ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Phosphate Transport ◽  
Mouse Kidney ◽  
Brush Border Membrane Vesicles ◽  
Low Phosphorus

We studied (1) the effect of primary modulators of phosphate transport, namely the hypophosphataemic mouse mutant (Hyp) and low-phosphorus diet, on alkaline phosphatase activity in mouse renal-cortex brush-border membrane vesicles and (2) the effect of several primary inhibitors of alkaline phosphatase on phosphate transport. Brush-border membrane vesicles from Hyp-mouse kidney had 50% loss of Na+-dependent phosphate transport, but only 18% decrease in alkaline phosphatase activity. The low-phosphorus diet effectively stimulated Na+/phosphate co-transport in brush-border membrane vesicles (+ 118%), but increased alkaline phosphatase activity only slightly (+13%). Levamisole (0.1 mM) and EDTA (1.0 mM) inhibited brush-border membrane-vesicle alkaline phosphatase activity of 82% and 93% respectively, but had no significant effect on Na+/phosphate co-transport. We conclude that alkaline phosphatase does not play a direct role in phosphate transport across the brush-border membrane of mouse kidney.

Phosphate transport and alkaline phosphatase in confluent MDCK cell monolayers

1987 ◽  
Vol 65 (6) ◽  
pp. 1151-1156 ◽  
Author(s):  
Marc Letellier ◽  
Normand Brière ◽  
Gérard E. Plante ◽  
Claude Petitclerc
Keyword(s):  
Alkaline Phosphatase ◽  
Phosphatase Activity ◽  
Alkaline Phosphatase Activity ◽  
Brush Border ◽  
Mdck Cell ◽  
Inorganic Phosphate ◽  
Brush Border Membrane ◽  
Phosphate Transport ◽  
Cell Monolayers ◽  
Sodium Dependent

Several studies have suggested that the brush border membrane alkaline phosphatase is involved in the renal reabsorption of inorganic phosphate along the proximal convoluted tubule. However, other studies on the influence of l(−)bromotetramisole, an inhibitor of alkaline phosphatase, upon phosphate transport into brush border membrane vesicles have failed to show an involvement of alkaline phosphatase. The present experiments were designed to demonstrate that the MDCK (Madin, Darby, canine, kidney) cell line can be used as an alternative model to study phosphate transport, to examine the effect of l(−)bromotetramisole and the role of alkaline phosphatase. MDCK cell monolayers were concomitantly used for alkaline phosphatase activity measurement and phosphate transport analysis. While alkaline phosphatase activity increases by 37-fold from day 2 to day 8 of culture, reaching a plateau at day 10, the sodium-dependent phosphate transport into the cell monolayers decreases by 2-fold during that same period. The phosphate transport was also studied in the presence of l(−)bromotetramisole at pH 8.5. The sodium-dependent phosphate uptake of inorganic phosphate is reduced by 43% in the presence of l(−)bromotetramisole at day 3 of culture but is not reduced in the 7-day-old culture. Our results suggest a participation of alkaline phosphatase upon phosphate transport in MDCK cell monolayers and indicate that this cell line constitutes a good model to study the relationship between alkaline phosphatase and phosphate transport.

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