NaPi-mediated Transcellular Permeation is the Dominant Route in Intestinal Inorganic Phosphate Absorption in Rats

2006 ◽  
Vol 21 (3) ◽  
pp. 217-221 ◽  
Author(s):  
Nobuaki Eto ◽  
Mikio Tomita ◽  
Masahiro Hayashi
1979 ◽  
Vol 56 (5) ◽  
pp. 407-412 ◽  
Author(s):  
J. Walton ◽  
T. K. Gray

1. Intestinal phosphate absorption in human subjects was studied by the technique of triple lumen intestinal perfusion in vivo. 2. Ileal phosphate absorption increased as the intraluminal phosphate concentration was increased. 3. Ileal rates of phosphate absorption were lower at any given intraluminal phosphate concentration than previously described jejunal rates. Acidification of the ileal lumen did not increase phosphate absorption. 4. Phosphate absorption was shown in the jejunum to be dependent on the intraluminal sodium concentration. 5. Phosphate absorption in the human small intestine consists of at least two components, one directly proportional to water movement and the second apparently independent of water movement.


1976 ◽  
Vol 231 (3) ◽  
pp. 979-985 ◽  
Author(s):  
VW Dennis ◽  
PB Woodhall ◽  
RR Robinson

The characteristics of inorganic phosphate transport in isolated perfused proximal tubules of the rabbit were examined using radioisotopic techniques. When tubules were perfused with an ultrafiltrate of rabbit serum, the mean lumen-to-bath flux of phosphate in the convoluted segment was 6.60 +/- 1.41 (SE) pmol/mm-min with a simultaneous back-to-lumen flux of 0.45 +/- 0.08. In the straight portion of the proximal tubule, the lumen-to-bath flux was significantly lower (P less than 0.01) at 2.22 +/- 0.48 pmol/min-min with a bath-to-lumen flux of 0.31 +/- 0.05. The lumen-to-bath flux was not affected by increases in the intraluminal phosphate concentration from 2.00 +/- 0.19 to 3.12 +/- 0.34 mM or by the isohydric replacement of bicarbonate in the ambient fluids with chloride. However, phosphate absorption was completely inhibited by ouabain 10(-5) M in the bath. These data indicate that phosphate absorption in these segments occurs by a mechanism other than independent diffusion and is saturated at phosphate concentrations characteristic of normal glomerular filtrate. There is no evidence for significant phosphate transport from bath to lumen.


Author(s):  
F. B. P. Wooding ◽  
K. Pedley ◽  
N. Freinkel ◽  
R. M. C. Dawson

Freinkel et al (1974) demonstrated that isolated perifused rat pancreatic islets reproduceably release up to 50% of their total inorganic phosphate when the concentration of glucose in the perifusion medium is raised.Using a slight modification of the Libanati and Tandler (1969) method for localising inorganic phosphate by fixation-precipitation with glutaraldehyde-lead acetate we can demonstrate there is a significant deposition of lead phosphate (identified by energy dispersive electron microscope microanalysis) at or on the plasmalemma of the B cell of the islets (Fig 1, 3). Islets after incubation in high glucose show very little precipitate at this or any other site (Fig 2). At higher magnification the precipitate seems to be intracellular (Fig 4) but since any use of osmium or uranyl acetate to increase membrane contrast removes the precipitate of lead phosphate it has not been possible to verify this as yet.


2013 ◽  
Vol 41 (05) ◽  
pp. 289-296 ◽  
Author(s):  
K. Seyrek-Intas ◽  
K. Failing ◽  
G. Yilmazbas Mecitoglu ◽  
H. Bostedt ◽  
D. Seyrek-Intas

Summary Objective: To determine the intravascular electrolyte status in dairy cows with respect to age and different courses of parturition to clarify etiological factors influencing peri- or intrapartal imbalances of electrolyte homeostasis. Material and methods: A total of 64 cows at birth were evaluated (primiparous n = 34, pluriparous n = 30). Thirty-three cows showed normal delivery, while 31 cows had a complicated birth. Blood samples were collected intra partum (i. p.) and 2, 4, 6, 8, 12, 16, 24 h post partum (p. p.) as well as [2, 3, 4, 5, 7, 10 days p. p. and levels of total calcium (Catotal), ionized calcium (Caion), inorganic phosphate (Pa), Mg, Na, K, Cl were determined. Results: The results revealed that electrolytes show great fluctuation during and immediately p. p. in relation to age. Already during parturition pluriparous cows had a lower Catotal and Pa concentration compared to primiparous animals. Cows with dystocia exhibited a more intensive and longer lasting decrease of Ca compared to cows with normal birth. In relation to age and severity of birth Pa concentration showed a differing but basically typical course for this electrolyte. Mg, Na, K and Cl concentrations were higher during and immediately after birth compared to p. p. values. Until day 10 p. p. these electrolyte concentrations declined more in older cows with dystocia compared to younger animals. However, the influence of dystocia on concentration of these electrolytes was milder in contrast to Ca and Pa. Conclusions: In summary, primarily older cows are predisposed to imbalances of electrolyte homeostasis intra partum and at the beginning of the lactation. These changes are potentiated in case of complications during parturition. Intravascular Catotal, Caion as well as Pa are most severely affected. Clinical relevance: These results may constitute the basis for a comprehensive metaphylaxis during the peripartal period, especially in cows after dystocia, to positively influence the early convalescence phase.


2018 ◽  
Author(s):  
Yingqian Wang ◽  
Xiaoxia Hu ◽  
Lingling Zhang ◽  
Chunli Zhu ◽  
Jie Wang ◽  
...  

Extracellular vesicles (EVs) are involved in the regulation of cell physiological activity and the reconstruction of extracellular environment. Matrix vesicles (MVs) are a type of EVs, and they participate in the regulation of cell mineralization. Herein, bioinspired MVs embedded with black phosphorus are functionalized with cell-specific aptamer (denoted as Apt-bioinspired MVs) for stimulating biomineralization. The aptamer can direct bioinspired MVs to targeted cells, and the increasing concentration of inorganic phosphate originated from the black phosphorus can facilitate cell biomineralization. The photothermal effect of the Apt-bioinspired MVs also positively affects mineralization. In addition, the Apt-bioinspired MVs display outstanding bone regeneration performance. Considering the excellent behavior of the Apt-bioinspired MVs for promoting biomineralization, our strategy provides a way of designing bionic tools for studying the mechanisms of biological processes and advancing the development of medical engineering.<br>


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