scholarly journals Alligators and Crocodiles Have High Paracellular Absorption of Nutrients, But Differ in Digestive Morphology and Physiology

2015 ◽  
Vol 55 (6) ◽  
pp. 986-1004 ◽  
Author(s):  
C. R. Tracy ◽  
T. J. McWhorter ◽  
C. M. Gienger ◽  
J. M. Starck ◽  
P. Medley ◽  
...  
Keyword(s):  
Paracellular Absorption

scholarly journals The Na+/H+ exchanger isoform 3 is required for active paracellular and transcellular Ca2+ transport across murine cecum

2013 ◽  
Vol 305 (4) ◽  
pp. G303-G313 ◽  
Author(s):  
Juraj Rievaj ◽  
Wanling Pan ◽  
Emmanuelle Cordat ◽  
R. Todd Alexander
Keyword(s):  
Water Movement ◽  
Water Flux ◽  
Wild Type Mouse ◽  
Wild Type ◽  
Rt Pcr ◽  
Ussing Chambers ◽  
Voltage Clamps ◽  
Paracellular Absorption ◽  
Mouse Intestine

Intestinal calcium (Ca2+) absorption occurs via paracellular and transcellular pathways. Although the transcellular route has been extensively studied, mechanisms mediating paracellular absorption are largely unexplored. Unlike passive diffusion, secondarily active paracellular Ca2+ uptake occurs against an electrochemical gradient with water flux providing the driving force. Water movement is dictated by concentration differences that are largely determined by Na+ fluxes. Consequently, we hypothesized that Na+ absorption mediates Ca2+ flux. NHE3 is central to intestinal Na+ absorption. NHE3 knockout mice (NHE3−/−) display impaired intestinal Na+, water, and Ca2+ absorption. However, the mechanism mediating this latter abnormality is not clear. To investigate this, we used Ussing chambers to measure net Ca2+ absorption across different segments of wild-type mouse intestine. The cecum was the only segment with net Ca2+ absorption. Quantitative RT-PCR measurements revealed cecal expression of all genes implicated in intestinal Ca2+ absorption, including NHE3. We therefore employed this segment for further studies. Inhibition of NHE3 with 100 μM 5-( N-ethyl- N-isopropyl) amiloride decreased luminal-to-serosal and increased serosal-to-luminal Ca2+ flux. NHE3−/− mice had a >60% decrease in luminal-to-serosal Ca2+ flux. Ussing chambers experiments under altered voltage clamps (−25, 0, +25 mV) showed decreased transcellular and secondarily active paracellular Ca2+ absorption in NHE3−/− mice relative to wild-type animals. Consistent with this, cecal Trpv6 expression was diminished in NHE3−/− mice. Together these results implicate NHE3 in intestinal Ca2+ absorption and support the theory that this is, at least partially, due to the role of NHE3 in Na+ and water absorption.

scholarly journals Intestinal Absorption Profile of Three Polygala Oligosaccharide Esters in Polygalae Radix and the Effects of Other Components in Polygalae Radix on Their Absorption

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
YinYing Ba ◽  
MengLin Wang ◽  
KunFeng Zhang ◽  
QiJun Chen ◽  
JiaJia Wang ◽  
...  
Keyword(s):  
Future Research ◽  
Active Components ◽  
Sodium Caprate ◽  
P Glycoprotein ◽  
Paracellular Absorption ◽  
Underlying Mechanisms ◽  
The Relationship ◽  
Rat Gut ◽  
Human Nervous System

Oligosaccharide esters, which are among the main active components of Polygalae Radix (PR), demonstrate significant pharmacological activities in the human nervous system. In our previous research, some other constituents in PR were able to improve the bioavailability of oligosaccharide esters such as sibiricose A5 (SA5), sibiricose A6 (SA6), and 3,6′-disinapoyl sucrose (DISS), but the related components and their underlying mechanisms remain unknown. The present study aimed to investigate the intestinal absorptive profile of SA5, SA6, and DISS and the absorptive behavior influenced by the coadministration of polygalaxanthone III and total saponins of PR (TS) using an in vitro everted rat gut sac model, along with the possible mechanisms that may influence absorption. The results showed that TS could significantly enhance the absorption of SA5, SA6, and DISS monomers. Verapamil, a P-glycoprotein inhibitor, was able to elevate the absorption of SA5 and SA6, and an absorption experiment using Rho123 led us to conclude that TS influenced the absorption of SA5 and SA6 in a manner similar to that of a P-glycoprotein inhibitor. Sodium caprate, a paracellular absorption enhancer, was found to increase the absorption of SA5, SA6, and DISS. Results showed that the absorption mechanisms of SA5 and SA6 may combine active transport with paracellular passive penetration, while DISS’s absorption was dominated by paracellular passive penetration. However, the relationship between polygala saponins and the absorption of SA5, SA6, and DISS by paracellular passive penetration remain to be examined. This is the direction of our future research.

Allometry of Paracellular Absorption in Birds

2008 ◽  
Vol 81 (5) ◽  
pp. 551-560 ◽  
Author(s):  
Shana R. Lavin ◽  
William H. Karasov
Keyword(s):  
Paracellular Absorption

scholarly journals Drinking and Water Handling in the Medaka Intestine: A Possible Role of Claudin-15 in Paracellular Absorption?

2020 ◽  
Vol 21 (5) ◽  
pp. 1853
Author(s):  
Christian K. Tipsmark ◽  
Andreas M. Nielsen ◽  
Maryline C. Bossus ◽  
Laura V. Ellis ◽  
Christina Baun ◽  
...  
Keyword(s):  
Water Transport ◽  
Physiological Role ◽  
Japanese Medaka ◽  
Apparent Difference ◽  
Drinking Rate ◽  
Functional Changes ◽  
Water Handling ◽  
Paracellular Absorption ◽  
The Stability

When euryhaline fish move between fresh water (FW) and seawater (SW), the intestine undergoes functional changes to handle imbibed SW. In Japanese medaka, the potential transcellular aquaporin-mediated conduits for water are paradoxically downregulated during SW acclimation, suggesting paracellular transport to be of principal importance in hyperosmotic conditions. In mammals, intestinal claudin-15 (CLDN15) forms paracellular channels for small cations and water, which may participate in water transport. Since two cldn15 paralogs, cldn15a and cldn15b, have previously been identified in medaka, we examined the salinity effects on their mRNA expression and immunolocalization in the intestine. In addition, we analyzed the drinking rate and intestinal water handling by adding non-absorbable radiotracers, 51-Cr-EDTA or 99-Tc-DTPA, to the water. The drinking rate was >2-fold higher in SW than FW-acclimated fish, and radiotracer experiments showed anterior accumulation in FW and posterior buildup in SW intestines. Salinity had no effect on expression of cldn15a, while cldn15b was approximately 100-fold higher in FW than SW. Despite differences in transcript dynamics, Cldn15a and Cldn15b proteins were both similarly localized in the apical tight junctions of enterocytes, co-localizing with occludin and with no apparent difference in localization and abundance between FW and SW. The stability of the Cldn15 protein suggests a physiological role in water transport in the medaka intestine.

Oleic acid and docosahexaenoic acid cause an increase in the paracellular absorption of hydrophilic compounds in an experimental model of human absorptive enterocytes

Toxicology ◽  
2007 ◽  
Vol 237 (1-3) ◽  
pp. 12-23 ◽  
Author(s):  
Bitte Aspenström-Fagerlund ◽  
Linda Ring ◽  
Pontus Aspenström ◽  
Jonas Tallkvist ◽  
Nils-Gunnar Ilbäck ◽  
...  
Keyword(s):  
Oleic Acid ◽  
Docosahexaenoic Acid ◽  
Experimental Model ◽  
Paracellular Absorption ◽  
Hydrophilic Compounds ◽  
Absorptive Enterocytes

scholarly journals The sweet life: diet sugar concentration influences paracellular glucose absorption

2008 ◽  
Vol 4 (5) ◽  
pp. 530-533 ◽  
Author(s):  
Kathryn R Napier ◽  
Cromwell Purchase ◽  
Todd J McWhorter ◽  
Susan W Nicolson ◽  
Patricia A Fleming
Keyword(s):  
Glucose Absorption ◽  
Paracellular Permeability ◽  
Sugar Concentration ◽  
Dynamic State ◽  
Intestinal Lumen ◽  
Future Studies ◽  
Relative Contribution ◽  
Rapid Absorption ◽  
Paracellular Absorption ◽  
Total Glucose

Small birds and bats face strong selection pressure to digest food rapidly in order to reduce digesta mass carried during flight. One mechanism is rapid absorption of a high proportion of glucose via the paracellular pathway (transfer between epithelial cells, not mediated by transporter proteins). Intestinal paracellular permeability to glucose was assessed for two nectarivorous passerines, the Australian New Holland honeyeater ( Phylidonyris novaehollandiae ) and African white-bellied sunbird ( Cinnyris talatala ) by measuring the bioavailability of radiolabelled, passively absorbed l -glucose. Bioavailability was high in both species and increased with diet sugar concentration (honeyeaters, 37 and 81% and sunbirds, 53 and 71% for 250 and 1000 mmol l −1 sucrose diets, respectively). We conclude that the relative contribution of paracellular to total glucose absorption increases with greater digesta retention time in the intestine, and paracellular absorption may also be modulated by factors such as intestinal lumen osmolality and interaction with mediated glucose uptake. The dynamic state of paracellular absorption should be taken into account in future studies.

P49 Paracellular absorption enhancement in intestinal CACO-2 monolayers by sodium caprate

1994 ◽  
Vol 2 (1-2) ◽  
pp. 131
Author(s):  
T. Lindmark ◽  
N. Schipper ◽  
L. Lazorova ◽  
A.G. de Boer ◽  
P. Artursson
Keyword(s):  
Absorption Enhancement ◽  
Sodium Caprate ◽  
Paracellular Absorption

scholarly journals Molecular support for high paracellular absorption in the intestine of flying mammals (1109.18)

2014 ◽  
Vol 28 (S1) ◽  
Author(s):  
Enrique Caviedes‐Vidal ◽  
Antonio Brun ◽  
Guido Fernández‐Marinone ◽  
Claudia Gatica‐Sosa ◽  
Edwin Price ◽  
...  
Keyword(s):  
Paracellular Absorption

FC 077LONG-TERM SAFETY OF TENAPANOR FOR THE CONTROL OF SERUM PHOSPHORUS IN PATIENTS WITH CKD ON DIALYSIS

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
Daniel Weiner ◽  
Steven Fishbane ◽  
Robert Lynn ◽  
Yang Yang ◽  
David Rosenbaum
Keyword(s):  
Adverse Events ◽  
Treatment Period ◽  
Serum Phosphorus ◽  
Withdrawal Period ◽  
Dialysis Patients ◽  
Open Label ◽  
Serious Adverse Events ◽  
Phosphate Absorption ◽  
Paracellular Absorption ◽  
Extension Period

Abstract Background and Aims Tenapanor, a first-in-class, phosphate absorption inhibitor blocks the paracellular absorption of phosphate in the GI tract by local inhibition of the sodium-hydrogen exchanger (NHE3). It therefore provides a novel, non-binder approach for managing hyperphosphatemia. Tenapanor is dosed as one small pill twice daily. In three pivotal trials, tenapanor met its primary phosphorus-lowering outcome. This report evaluates long-term safety data from the longest of these trials. Method This 52-week study consisted of a 26-week, open-label, randomized treatment period with a 12-week placebo-controlled randomized withdrawal period, followed by a 14-week open label safety extension period. Maintenance dialysis patients with serum phosphorus ≥ 6.0 mg/dL and a 1.5 mg/dL increase in serum phosphorus following phosphate binder washout were randomized 3:1 to receive tenapanor 30 mg twice daily or sevelamer carbonate, dosed per package insert. At end of the randomized treatment period all patients in the tenapanor arm were re-randomized 1:1 to either tenapanor or placebo for the randomized withdrawal period followed by tenapanor for the safety extension period. Sevelamer was used as a safety control for comparisons of serious adverse events/hospitalizations to tenapanor. Results Tenapanor was generally well tolerated, with diarrhea the only adverse event reported by >5% of patients during the randomized treatment period. Diarrhea was typically mild-to-moderate in severity, transient, and occurred more commonly during the randomized treatment period than the randomized withdrawal or safety extension periods. Rates of serious adverse events leading to hospitalization were higher in patients treated with sevelamer than tenapanor (35.8% vs 24.6%). The highest reported percentages of serious adverse events were infections and infestations (16.1% vs 9.3%) cardiac disorders (8.0% vs 5.7%), respiratory, thoracic and mediastinal disorders (8.8% vs 5.5%), and metabolism and nutritional disorders (7.3% vs 3.6%) for sevelamer and tenapanor, respectively. Adverse events leading to death were higher in patients treated with sevelamer than tenapanor (3.6% vs 2.9%). Conclusion Among maintenance dialysis patients with hyperphosphatemia, tenapanor, a novel, non-binder, phosphate absorption inhibitor that blocks paracellular absorption of phosphorus with a one tablet twice daily dose, has an acceptable safety profile, and, if approved, may offer a new approach to the treatment of hyperphosphatemia.

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