Regulation of phosphate transport by second messengers in capillaries of the blood-brain barrier

Dallaire, L; Giroux, Sylvie; Béliveau, Richard

doi:10.1016/0005-2736(92)90294-v

Cited by 10 publications

(9 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The functional and molecular nature of Na ϩ -independent P i transport remains elusive so far, and only a few classical works have made initial characterizations, such as P i -HCO 3 Ϫ exchange in capillaries of the blood-brain barrier, which is also inhibited by DIDS, SITS, sulfate, and other substrates (8). Our work represents an initial characterization of the intestinal Na ϩ -independent P i transport system, and the findings could help to identify the specific carriers by using alternative approaches.…”

Section: Discussionmentioning

confidence: 99%

Na⁺-independent phosphate transport in Caco2BBE cells

Candeal

Caldas

Guillén

et al. 2014

American Journal of Physiology-Cell Physiology

View full text Add to dashboard Cite

i transport in epithelia has both Na ϩ -dependent and Na ϩ -independent components, but so far only Na ϩ -dependent transporters have been characterized in detail and molecularly identified. Consequently, in the present study, we initiated the characterization and analysis of intestinal Na ϩ -independent P i transport using an in vitro model, Caco2BBE cells. Only Na ϩ -independent Pi uptake was observed in these cells, and Pi uptake was dramatically increased when cells were incubated in high-P i DMEM (4 mM) from 1 day to several days. No response to low-Pi medium was observed. The increased Pi transport was mainly caused by V max changes, and it was prevented by actinomycin D and cycloheximide. Pi transport in cells grown in 1 mM Pi (basal DMEM) decreased at pH Ͼ 7.5, and it was inhibited with proton ionophores. Pi transport in cells incubated with 4 mM Pi increased with alkaline pH, suggesting a preference for divalent phosphate. Pi uptake in cells in 1 mM Pi was completely inhibited only by Pi and partially inhibited by phosphonoformate, oxalate, DIDS, SITS, SO 4 2Ϫ , HCO 3 Ϫ , and arsenate. This inhibition pattern suggests that more than one Pi transporter is active in cells maintained with 1 mM Pi. Phosphate transport from cells maintained at 4 mM Pi was only partially inhibited by phosphonoformate, oxalate, and arsenate. Attempts to identify the responsible transporters showed that multifunctional anion exchangers of the Slc26 family as well as members of Slc17, Slc20, and Slc37 and the Pi exporter xenotropic and polytropic retrovirus receptor 1 are not involved. phosphate transport; Caco2BBE cells; Na ϩ -independent Pi uptake; phosphate absorption; small intestine; inorganic phosphate CONTROL of P i homeostasis is mediated by the coordinated activity of a complex set of physiological mechanisms acting on the rate of intestinal absorption, rate of renal excretion, and eventual mobilization of the bone reservoir. These mechanisms consist of hormones and nonhormonal events that act either acutely or slowly (chronically) to modulate the activity of plasma membrane P i transporters (2, 4, 23). The precision of P i homeostasis control is critical not only because of the extreme relevance of the physiological roles of P i in the organism (pH buffer, energy bonds, signal transduction, phospholipid composition, bone formation, etc.) but also because serious conditions can emerge when control of P i homeostasis is lost, resulting in either hypophosphatemia (7) or hyperphosphatemia (20,23).While the kidney has historically been recognized as the major checkpoint and regulator of P i homeostasis, more recently it has been revealed that the intestine is a relevant modulator of P i signaling and is now a target for pharmacological interventions in phosphate disorders (23,30,31). The majority of P i absorption takes place in the small intestine, with important regional differences depending on the animal species (22). With respect to the mechanisms of P i absorption, the classical combination of both saturated (transcel...

show abstract

Section: Discussionmentioning

confidence: 99%

Na⁺-independent phosphate transport in Caco2BBE cells

Candeal

Caldas

Guillén

et al. 2014

American Journal of Physiology-Cell Physiology

View full text Add to dashboard Cite

show abstract

“…The observations that (1) Na+-dependent Pi uptake is unaffected by 1 mM DIDS and (2) the Pi self-exchange system operates under Na+-free conditions provide evidence that this process is not mediated by the Na'-Pi cotransport mechanism. In one experiment we failed to find any effect of extracellular HCO3-on Pi efflux, suggesting that the self-exchange system is distinct from the exchange pathway which has been described in brain tissue and which appears to function as a Pi-HCO3-exchanger (Dallaire & Beliveau, 1992). The physiological significance of the mammary Pi self-exchanger remains to be determined.…”

Section: Cation Dependence Of Pi Uptake By Mammary Tissue Explantsmentioning

confidence: 77%

“…In some cells Pi transport has been shown to be mediated via an anion exchange system (e.g. see Brauer, Spread, Reithmeier & Sykes, 1985;Dallaire & Beliveau, 1992). In view of this, we decided to test whether Pi transport in lactating mammary tissue could be mediated by an exchange pathway.…”

Section: Cation Dependence Of Pi Uptake By Mammary Tissue Explantsmentioning

confidence: 99%

Phosphate transport via Na+ ‐Pi cotransport and anion exchange in lactating rat mammary tissue

Jm¹,

Calvert²,

Beechey³

et al. 1996

Experimental Physiology

View full text Add to dashboard Cite

SUMMARYInorganic orthophosphate (P1) transport, using 32P-labelled orthophosphate as tracer, by lactating rat mammary tissue has been examined using both tissue explants and the intact perfused gland. Pi uptake was predominantly via a Na+-dependent pathway. Li', however, unlike choline, was able to partially substitute for Na+. In addition, Pi release from tissue explants preloaded with 32Pi was stimulated by reversing the Na+ gradient. Thus transferring mammary explants from a buffer containing Na+ to one which was Na+ free (choline replacement) doubled the P1 efflux rate constant. The uptake of Pi by tissue explants was saturable with respect to external Pi, having apparent Km and Vmax values of 1 13 mm and 3 36 mmol (kg cell water)-' (15 min)-', respectively.The stimulation of Pi uptake by tissue explants by external Na+ was also saturable; the K. for Na+ was 9-7 mm. These results, taken together, suggest that the Na+-dependent pathway is a Na'-P, cotransport mechanism. The transport of Pi by the perfused lactating rat mammary gland was examined using a rapid, paired-tracer dilution technique. P1 uptake by the perfused gland was found to be Na+ dependent and displayed saturable kinetics. The results suggest that the Na+-P, cotransporter is situated at the basolateral aspect of the secretory cells. The release of Pi from preloaded tissue explants was trans-accelerated by external Pi but not by Cl-or s042-. However, external Pi stimulated Pi efflux with low affinity.

show abstract

“…In some tissues such as isolated bovine capillaries, however, Ang II does not affect phosphate transport [27] suggesting that the effect of Ang II impacts the type III sodium-dependent phosphate cotransporter. In contrast to Ang II, ET-1 has been consistently demonstrated to increase cellular phosphate transport.…”

Section: Phosphate Transport Into Cells: Contrasting Effects Of Etmentioning

confidence: 99%

Endothelin but Not Angiotensin II May Mediate Hypertension-Induced Coronary Vascular Calcification in Chronic Kidney Disease

Rabkin

2011

International Journal of Nephrology

View full text Add to dashboard Cite

To understand the relationship between putative neurohormonal factors operative in hypertension and coronary artery calcification (CAC), the relevant cellular actions of angiotensin (Ang II) and endothelin-1 (ET-1) are reviewed. There is compelling evidence to implicate ET-1 in CAC. ET-1 increases phosphate transport with a 42 to 73% increase in Vmax. Increased cellular phosphate may induce CAC through increased Ca x phosphate product, transformation of vascular smooth muscle cells into a bone-producing phenotype or cell apoptosis that releases procalcific substances. ET-1 is increased in several models of vascular calcification. ET-1 inhibits inhibitors of calcification, matrix Gla and osteoprotegerin, while enhancing pro-calcific factors such as BMP-2 and osteopontin. In contrast, Ang II inhibits phosphate transport decreasing Vmax by 38% and increases matrix Gla. Ang II also stimulates bone resorption. Vascular calcification is reduced by ET-1 A receptor antagonists and to a greater extent than angiotensin receptor blockade although both agents reduce blood pressure.

show abstract

Regulation of phosphate transport by second messengers in capillaries of the blood-brain barrier

Cited by 10 publications

References 25 publications

Na⁺-independent phosphate transport in Caco2BBE cells

Na⁺-independent phosphate transport in Caco2BBE cells

Phosphate transport via Na+ ‐Pi cotransport and anion exchange in lactating rat mammary tissue

Endothelin but Not Angiotensin II May Mediate Hypertension-Induced Coronary Vascular Calcification in Chronic Kidney Disease

Contact Info

Product

Resources

About

Regulation of phosphate transport by second messengers in capillaries of the blood-brain barrier

Cited by 10 publications

References 25 publications

Na+-independent phosphate transport in Caco2BBE cells

Na+-independent phosphate transport in Caco2BBE cells

Phosphate transport via Na+ ‐Pi cotransport and anion exchange in lactating rat mammary tissue

Endothelin but Not Angiotensin II May Mediate Hypertension-Induced Coronary Vascular Calcification in Chronic Kidney Disease

Contact Info

Product

Resources

About

Na⁺-independent phosphate transport in Caco2BBE cells

Na⁺-independent phosphate transport in Caco2BBE cells