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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Transforming growth factor beta 1 modulates electrophysiological parameters of vas deferens epithelial cells

Yi, Sheng January 1900 (has links)
Doctor of Philosophy / Department of Anatomy and Physiology / Bruce Schultz / Transforming growth factor β1 (TGF-β1) is a cytokine that reportedly affects the severity of cystic fibrosis lung disease. The goal of this project was to define the effect of TGF-β1 on vas deferens, an organ that is universally affected in male cystic fibrosis patients. In the first study, experiments were conducted using freshly isolated porcine vas deferens epithelial cells. Primary porcine vas deferens epithelial cells exposed to TGF-β1 exhibited a significantly reduced basal transepithelial electrical resistance (Rte). TGF-β1-induced reduction in Rte was prevented by SB431542, a TGF-β receptor I inhibitor, indicating that the effect of TGF-β1 requires the activation of TGF-β receptor I. Western blot and immunohistochemistry results showed the expression of TGF-β receptor I in native vas deferens epithelia, indicating that the impaired barrier function and anion secretion that were observed in cultured vas deferens cells can likely be observed in the native context. Immunohistochemical outcomes showed that TGF-β1 exposure led to loss of organization of tight junction proteins occludin and claudin-7. These outcomes suggest that TGF-β1 impairs the barrier integrity of epithelial cells lining the vas deferens. In a parallel study that employed PVD9902 cells that are derived from porcine vas deferens, TGF-β1 exposure significantly reduced anion secretion stimulated by forskolin, forskolin/IBMX, and 8-pCPT-cAMP, suggesting that TGF-β1 affects downstream targets of the cAMP signaling pathway. Real-time RT-PCR and western blot analysis showed that TGF-β1 exposure reduced both the mRNA and the protein abundance of cystic fibrosis transmembrane conductance regulator (CFTR). Pharmacological studies showed that the inhibitory effect of TGF-β1 on forskolin-stimulated anion secretion was abrogated by SB431542 and attenuated by SB203580, a p38 mitogen-activated protein kinase (MAPK) inhibitor. These outcomes suggest that TGF-β1, via the activation of TGF-β receptor I and p38 MAPK signaling, reduces CFTR expression, and thus impairs CFTR-mediated anion secretion. Outcomes from these studies suggest that, in epithelial cells lining the vas deferens, TGF-β1 exposure leads to an impaired physical barrier and/or reduced anion secretion, which is expected to modify the composition and the maintenance of the luminal environment and thus, is expected to reduce male fertility.
32

Coping with salinity and temperature changes : a focus on the gill response in European sea bass Dicentrarchus labrax / S'acclimater à des salinités et températures changeantes : un focus sur la branchie chez le loup européen Dicentrarchus labrax

Masroor, Waliullah 26 April 2019 (has links)
Le loup ou bar européen effectue une partie de son cycle de vie dans les lagunes et estuaires, des eaux de transitions caractérisées par des fluctuations environnementales plus marquées qu’en milieu marin. Les mécanismes d’acclimatation à la salinité à des températures plus élevées qu’en milieu marin sont encore relativement inexplorés. Dans cette étude, des juvéniles de loup ont été préacclimatés pendant deux semaines à l’eau de mer (EM) à 18 °C (eau tempérée) ou à 24 °C (eau chaude) puis transférés soit dans l’eau douce (ED) soit dans l’EM aux deux températures testées. À 24 °C, les loups parviennent à maintenir leur pression osmotique sanguine relativement constante, quelle que soit la salinité testée. En revanche, la hausse de température affecte significativement différents traits physiologiques liés à l’osmorégulation, la régulation acido- basique, l’excrétion azotée et la production de mucus. Cette étude a notamment montré qu’une acclimatation thermique à 24 °C modifie la structure morphologique de la branchie et induit un déséquilibre de la balance ionique sanguine. Ce déséquilibre concerne particulièrement les ions Na+ et a pour conséquence une diminution du ratio Na+/Cl- plasmatique, pouvant être symptomatique d’une acidose sanguine. Après transfert en douce, une augmentation moins importante de la densité des ionocytes branchiaux et de l’activité de la pompe Na+/K+ ATPase a été observée à 24 °C comparé à 18 °C. De plus, certains transporteurs ioniques jouant un rôle clé dans l’absorption ionique en eau douce n’ont pas été induits au niveau transcriptionnel à 24 °C. Cela suggère une capacité réduite des poissons de passer d’un épithélium branchial hypo-osmorégulateur vers un épithélium hyper-osmorégulateur lors d’un transfert en eau douce à 24 °C vs 18 °C. Au niveau moléculaire, la hausse de température a affecté l’expression de plusieurs transporteurs ioniques branchiaux, notamment en EM. À 24 °C, la surexpression de transporteurs liés au transport de proton H+ pourrait être le signe d’un déséquilibre acido- basique. De plus, l’induction de transporteurs d’ammonium pourrait indiquer un besoin accru d’excréter de l’azote par voie branchiale, potentiellement lié à un métabolisme plus élevé en eau chaude. L’expression des gènes codant pour la protéine chaperonne HSP90 a été fortement affectée par la hausse de température et dans une moindre mesure par la dessalure. Pour finir, l’analyse des mucocytes suggère que la production de mucus pourrait être induite en réponse au stress thermique. Ce type d’étude fonctionnelle sur l’acclimatation à différents régimes de température permet d’apporter des éléments de compréhension pour pouvoir prédire les réponses des téléostéens face aux conséquences du changement global. / The European sea bass Dicentrarchus labrax undertakes seasonal migrations to estuaries and lagoons that are characterized by fluctuations in environmental conditions. It is unclear to what extent salinity acclimation mechanisms are affected at temperatures higher than in the sea, as usually encountered in transitional waters in spring and summer. In this study, juvenile sea bass were pre-acclimated to seawater (SW) at 18 °C (temperate) or 24 °C (warm) for two weeks and then transferred to either fresh water (FW) or SW at the considered temperatures. We have shown that sea bass are able to efficiently maintain blood osmolality at 24 °C at both salinities. However, temperature increase induced significant changes regarding several physiological traits related to osmoregulation, acid-base regulation, ammonia excretion and mucus production. This study showed that thermal acclimation at 24 °C affects gill morphology through gill remodeling and whole-organism ion balance. Plasma Na+ levels seemed to be particularly affected leading to decreased plasma Na+/Cl- ratio in warm conditions, suggesting a blood acidosis. Following FW transfer, the major effects observed were a lower increase in the density of branchial ionocytes and in Na+/K+-ATPase activity at 24 °C compared to 18 °C. Moreover, several key ion transporters involved in ion uptake were not transcriptionally induced following FW transfer at 24 °C. These data suggest a less effective capacity to switch from hypo-to hyper-osmoregulation after FW transfer when fish are exposed to higher temperature. At the molecular level, the temperature increase affected the expression of several branchial transporters, notably in SW. At 24 °C, higher expression of transporters linked to H+ transport might be linked to an acid-base imbalance. Moreover, the induction of ammonia-transporting channels might also indicate increased need for nitrogen excretion, potentially due to enhanced metabolism in warm conditions. Molecular chaperones HSP90 expression was strongly affected by temperature increase and to a lesser extent by salinity decrease. Finally, gill goblet cells analysis suggested that mucus production is increased in response to thermal stress. This study and additional functional studies investigating different temperature regimes provide insights on the effect of increased temperatures on fish responses and may help to predict how teleost will face the consequences of global change.
33

The simultaneous measurement of nucleotide-stimulated cytosolic calcium signaling and anion secretion in cultured equine sweat gland epithelium.

January 2000 (has links)
Wong Hau Yan Connie. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 86-95). / Abstracts in English and Chinese. / Abstract --- p.ii / Acknowledgements --- p.ix / Contents --- p.x / List of Figures --- p.xiii / List of Tables --- p.xv / Abbreviations --- p.xvi / Chapter Chapter 1: --- Introduction / Chapter 1.1 --- Role of extracellular nucleotides in equine sweat gland epithelial cells --- p.1 / Chapter 1.2 --- Subdivision of P1 and P2 purinoceptor --- p.4 / Chapter 1.3 --- General properties of P2 purinoceptor --- p.5 / Chapter 1.3.1 --- P2X purinoceptor family --- p.5 / Chapter 1.3.2 --- P2Y purinoceptor family --- p.8 / Chapter 1.4 --- The diversity of P2Y purinoceptor --- p.10 / Chapter 1.4.1 --- P2Y1 receptor --- p.10 / Chapter 1.4.2 --- P2Y2 receptor --- p.10 / Chapter 1.4.3 --- P2Y4 receptor --- p.10 / Chapter 1.4.4 --- P2Y6 receptor --- p.10 / Chapter 1.4.5 --- P2Y11 receptor --- p.11 / Chapter 1.5 --- The importance of calcium --- p.13 / Chapter 1.6 --- General aspects of calcium signaling --- p.14 / Chapter 1.7 --- Calcium release from the intracellular calcium stores --- p.15 / Chapter 1.7.1 --- Metabolism of inositol phosphates --- p.15 / Chapter 1.7.2 --- Ca2+ release from the internal calcium store --- p.15 / Chapter 1.8 --- Store-operated calcium channels (SOCC) or Capacitative calcium entry (CCE) --- p.18 / Chapter 1.8.1 --- The nature of the signal for CCE --- p.18 / Chapter 1.8.1.1 --- Conformational coupling --- p.18 / Chapter 1.8.1.2 --- Diffusible messenger --- p.21 / Chapter 1.9 --- Mechanism of intracellular calcium measurement --- p.25 / Chapter 1.10 --- Background of E92/3 cell line --- p.28 / Chapter Chapter 2: --- Materials and methods --- p.29 / Chapter 2.1 --- Cell culture --- p.29 / Chapter 2.2 --- Preparation of the simultaneous measurement --- p.31 / Chapter 2.2.1 --- Cell seeding --- p.31 / Chapter 2.2.2 --- Dye loading --- p.33 / Chapter 2.3 --- The setup of simultaneous measurement --- p.36 / Chapter 2.4 --- Statistical analysis --- p.40 / Chapter Chapter 3: --- Results --- p.41 / Chapter 3.1 --- Major domain of Ca2+ influx is from the basolateral side --- p.41 / Chapter 3.1.1 --- Effect of store depletion by apical ATP --- p.41 / Chapter 3.1.2 --- Effect of store depletion by basolateral ATP --- p.43 / Chapter 3.1.3 --- Effect of store depletion by thapsigargin --- p.47 / Chapter 3.2 --- Differential effect of apical and basolateral nucleotides on [Ca2+]i and Isc --- p.51 / Chapter 3.2.1 --- Basolateral ATP activates an increase in [Ca2+]i but not Isc --- p.51 / Chapter 3.2.2 --- Apical and basolateral ATP activated distinct but partially overlapped internal Ca2+ pool --- p.51 / Chapter 3.2.3 --- "Dose-dependent effect of apical or basolateral ATP, UDP and UTP on [Ca2+]i i and Isc" --- p.54 / Chapter 3.3 --- P2Y receptors subtypes on the basolateral membrane --- p.60 / Chapter 3.3.1 --- "Possible involvement of P2X, P2Y1 and P2Y11 purinoceptors on the basolateral membrane" --- p.60 / Chapter 3.3.2 --- "Cross-desensitization of experiments of UTP, ATP and UDP" --- p.60 / Chapter 3.4 --- The ATP-activated Ca2+ pool and thapsigargin-activated Ca2+ pool are partially overlapped --- p.68 / Chapter 3.5 --- Anion secretion activated by Ca2+ -independent pathway --- p.74 / Chapter Chapter 4: --- Discussion --- p.76 / Chapter 4.1 --- The major membrane for the CCE is from the basolateral side --- p.76 / Chapter 4.2 --- Basolateral P2Y receptors --- p.80 / Chapter 4.3 --- Differential effects of apical and basolateral ATP --- p.82 / Chapter 4.3.1 --- Apical and basolateral ATP release Ca2+ from different pools --- p.83 / Chapter 4.3.2 --- Ca2+ -independent mechanism --- p.83 / Chapter 4.3.3 --- Other potential signaling molecules --- p.84 / Chapter Chapter 5: --- Reference --- p.86
34

Passagens de ions peróxido para a superfície dentária externa após clareamento com peróxido de hidrogênio /

Palo, Renato Miotto. January 2009 (has links)
Orientador: Idomeo Bonetti Filho / Banca: Cacio de Moura-Neto / Banca: Ivaldo gomes de Moraes / Banca: Marcia Carneiro Valera / Banca: Fabio Luiz Camargo Villela Berbert / Resumo: O objetivo deste trabalho foi avaliar a quantidade de peróxido que passa da câmara pulpar para a superfície dentária externa durante o clareamento interno no esmalte, cemento e dentina. Foram utilizados 50 incisivos bovinos extraídos que receberam aberturas coronárias, as raízes foram cortadas a 5 mm da junção amelo-cementária e foi realizado um tampão de 2mm de ionômero de vidro selando a entrada do canal. A extremidade apical dos espécimes foi isolada externamente com resina composta fotoativada. Os dentes foram então impermeabilizados completamente, deixando exposto somente as áreas a serem estudadas. As câmaras coronárias foram preenchidas com peróxido de hidrogênio a 35%. Os dentes foram divididos em três grupos experimentais e dois grupos controles, com 10 espécimes cada. GE - esmalte exposto a ser avaliado; GC - cemento exposto a ser avaliado; GD - dentina exposta a ser avaliada; e dois grupos Controle: GC1 - sem a presença de clareador internamente e sem impermeabilização e GC2 - câmara pulpar preenchida com clareador e impermeabilização total. Cada amostra foi colocado no interior de reservatórios individuais com 1000μl de solução tampão de acetato 2M (pH 4,5). Após 7 dias a 37±1ºC a solução foi transferida para um tubo de ensaio onde foram adicionados 100μl do corante violeta leucocristal e 50 μl de peroxidase, resultando em uma solução de coloração azul. A mensuração da absorbância foi feita em um espectrofotômetro e convertida em μg/ml de peróxido. Para avaliar se houve diferença entre os grupos experimentais e controle, realizou-se os testes de Kruskall-Walis e Dunn-Bunferroni e os resultados mostraram os íon passaram mais pela dentina exposta, seguida da dentina recoberta pelo esmalte e dentina recoberta pelo cemento, sem diferenças estatísticas. Todos os grupos experimentais foram diferentes dos controles... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aim of this study was evaluated the pulp chamber penetration of peroxide bleaching agent to the root surface during the internal bleach technique in the enamel, dentin and cement. Bovine teeth were sectioned 5mm apical of the cemento-enamel junction and was performed a 2mm cervical seal with glass ionomer cement. The external apical part of samples was filled with composite resin. The teeth were divided into three experimental groups and two control groups: GE - exposition of enamel; GC - exposition of cement; GD - exposition of dentin and control groups: GC1 - no presence of internal agent bleaching e no waterproof and GC2 - pulp chamber filled with bleaching agent and total waterproof. Each sample was placed inside of individual flasks with 1000μl of acetate buffer solution 2M (pH 4.5). After 7 days, the buffer solution was transferred to a glass tube where leuco crystal violet and horseradish peroxidase were added, producing a blue solution. The optical density of the blue solution was determined by spectrophotometer and converted into microgram equivalents of hydrogen peroxide. Data were submitted to Kruskal-Wallis, and Dunn-Bunferroni tests. The results showed that the ions penetration was higher in dentin followed by enamel and cement. All experimental groups presented statistical differences to the control groups. / Doutor
35

SYNTHESIS, FUNCTIONALIZATION, AND APPLICATION OF NANOFILTRATION AND COMPOSITE MEMBRANES FOR SELECTIVE SEPARATIONS

Colburn, Andrew Steven 01 January 2019 (has links)
Future nanofiltration (NF) membranes used for selective separations of ions and small organic molecules must maintain performance in environments where high concentrations of total dissolved solvents or foulants are present. These challenges can be addressed through the development of composite membranes, as well as the engineering of enhanced surface properties and operating conditions for existing commercial membranes. In this work, ion transport through commercial thin film composite (TFC) polyamide NF membranes were studied in both lab-prepared salt solutions and industrial wastewater. The dependence of several variables on ion rejection was investigated, including ion radius, ion charge, ionic strength, and temperature. The impact of scaling and increasing ionic concentration on membrane performance during recovery of industrial wastewater was investigated. Fouling of the membrane surface was reduced by enhancing commercial NF membrane surfaces via aqueous-phase esterification of lignin sulfonate. NF membranes were also created utilizing an ionic liquid solvent (1-ethyl-3-methylimidazolium acetate) to integrate composite materials into cellulose. Composite materials such as graphene oxide quantum dots, iron III particles, and lignin have been shown to be interact strongly with cellulose in solution with ionic liquid and bind together cellulose chains via hydrogen bonds following nonsolvent induced phase inversion. Studies suggest the composite materials modify membrane surface chemistry and improve selectivity of small organic molecules (~300 nm) while allowing for the complete passage of ions.
36

Regulation of the Lactoperoxidase System in the Airway

Fragoso, Miryam Araceli 14 December 2007 (has links)
The lactoperoxidase (LPO) antimicrobial system has been shown to play an important role in maintaining sterile conditions in several tissues including the mammary gland, the salivary gland, and the airway. The LPO system in the airway consists of the enzyme LPO and its substrates hydrogen peroxide and an anion. LPO catalyzes the oxidation of a halide or pseudohalide ion for example SCN-or I- by hydrogen peroxide producing a product, OSCN- or OI- which have antibacterial, antifungal, and antiviral properties. In order to have a functional antimicrobial system all the components need to be present at appropriate concentrations. The LPO system has been suggested to be deficient in cystic fibrosis. There are three possible regulatory mechanism of this antimicrobial system and these involve the secretion and availability of the three components of the LPO system in the luminal fluid. The studies presented in this dissertation examine two of the possible regulatory mechanisms of the LPO system in the airway; the availability and transport of SCN- to the luminal surface, and the expression of LPO. The knowledge obtained from these studies could be utilized to develop treatments to control infection in diseases characterized by chronic infections such as cystic fibrosis.
37

On the fluid mechanics of electrochemical coating and spray painting

Olivas, Pedro January 2001 (has links)
Finite-volume methods have been used for modeling of fluidflows involved in forced convection electrochemical coating androtating spray painting systems. Electrodeposition on a singlecircular cylinder under forced convection for Reynolds numbers10 and 200 was simulated. Comparisons with earlier numericaland theoretical results are presented and it is shown that theunsteady wake that appears for Reynolds numbers greater than 50affects the mass transfer from the surface of the cylinder onlyin an average sense. This result is compared with a heattransfer case, where unsteadiness is much more manifest. Theeffect of application of circulation movement around thecylinder surface was considered, showing that the use ofoptimal values for circulation can create a recirculation zonearound the cylinder and result in a remarkable improvement ofthe deposit uniformity. The magnetoelectrolysis researchdiscipline is presented with focus on magnetic fields uses onmass transfer processes. A classification of the governingdimensionless parameters that control the phenomena isproposed. Application of magnetoelectrolysis on electroplatingprocesses is done for the first time. It is found that the useof an alternating magnetically induced force around thecylinder can result in interesting improvement of quality andproductivity. Application of numerical methods is also studiedin another field of the surface finishing industry, thepainting atomizers. A critical situation of "reverse flow" isanalyzed. Different parameters of this phenomenon are studiedand suggestions for atomizers design are given and tested. <b>Keywords:</b>mass transfer, electrochemical coating, iontransport, forced convection, diffusion, magnetoelectrolysis,electrolyte, limiting current, numerical simulation,finite-volume methods, paint atomization, Coanda effect.
38

On the fluid mechanics of electrochemical coating and spray painting

Olivas, Pedro January 2001 (has links)
<p>Finite-volume methods have been used for modeling of fluidflows involved in forced convection electrochemical coating androtating spray painting systems. Electrodeposition on a singlecircular cylinder under forced convection for Reynolds numbers10 and 200 was simulated. Comparisons with earlier numericaland theoretical results are presented and it is shown that theunsteady wake that appears for Reynolds numbers greater than 50affects the mass transfer from the surface of the cylinder onlyin an average sense. This result is compared with a heattransfer case, where unsteadiness is much more manifest. Theeffect of application of circulation movement around thecylinder surface was considered, showing that the use ofoptimal values for circulation can create a recirculation zonearound the cylinder and result in a remarkable improvement ofthe deposit uniformity. The magnetoelectrolysis researchdiscipline is presented with focus on magnetic fields uses onmass transfer processes. A classification of the governingdimensionless parameters that control the phenomena isproposed. Application of magnetoelectrolysis on electroplatingprocesses is done for the first time. It is found that the useof an alternating magnetically induced force around thecylinder can result in interesting improvement of quality andproductivity. Application of numerical methods is also studiedin another field of the surface finishing industry, thepainting atomizers. A critical situation of "reverse flow" isanalyzed. Different parameters of this phenomenon are studiedand suggestions for atomizers design are given and tested.</p><p><b>Keywords:</b>mass transfer, electrochemical coating, iontransport, forced convection, diffusion, magnetoelectrolysis,electrolyte, limiting current, numerical simulation,finite-volume methods, paint atomization, Coanda effect.</p>
39

Understanding and engineering ion transport in conducting polymers.

Stavrinidou, Eleni 16 October 2013 (has links) (PDF)
Many organic electronic and bioelectronics devices rely on mixed (electronic and ionic) transport within a single organic layer. Although electronic transport in these materials is relatively well understood, a fundamental understanding of ion transport is missing. I developed a simple analytical model that describes ion transport in a planar junction between an electrolyte and a conducting polymer film. The model leads to predictions of the temporal evolution of drift length of ions and current. These predictions are validated by numerical simulations and by using realistic parameters, I show that the analytical model can be used to obtain the ion mobility in the film. Furthermore, I developed an experimental method which allows the application of the analytical model and leads to a straightforward estimation of the ion drift mobilities in conducting polymers. PEDOT:PSS was found to support efficient transport of common ions, consistent with extensive swelling of the film in water. Crosslinking the film decreased its swelling and the ion mobility. Understanding the high correlation of hydration and ionic conductivity enables us to engineer materials with high and defined ion mobilities. As an example tuning of ion mobility by adjusting the relative ratio of the hydroscopic phase to PEDOT:TOS is presented. Finally I performed electrochemical impedance spectroscopy during a moving front experiment, in order to give a physical interpretation of the impedance spectra at a conducting polymer/electrolyte junction.
40

FUNCTIONAL ADAPTATION OF THE RUMINAL EPITHELIUM

2013 December 1900 (has links)
Short chain fatty acids (SCFA) synthesized in the rumen from carbohydrate fermentation are an essential energy source for ruminants. Current literature supports that SCFA are absorbed across the rumen epithelium via passive diffusion or protein-mediated transport, however, the rate and degree to which these pathways adapt to a change in diet fermentability is unknown. Furthermore, Na+ flux is partially determined by SCFA absorption, and thus is a key indicator of functional changes in the rumen epithelium. The objectives of this study were to determine the time required for a change in SCFA and Na+ absorption across the bovine rumen epithelium and to evaluate the rate and degree to which absorption pathways adapt to an increase in diet fermentability relative to changes in surface area. Twenty-five weaned Holstein steer calves were blocked by body weight and randomly assigned to either the control diet (CON; 91.5% hay and 8.5% vitamin/mineral supplement) or a moderately fermentable diet (50% hay; 41.5% barley grain, and 8.5% vitamin/mineral supplement) fed for 3 (G3), 7 (G7), 14 (G14), or 21 d (G21). All calves were fed at 2.25% BW at 0800 h. Reticular pH was recorded every 5 min for 48 h prior to killing (1000 h). Ruminal tissue was collected for Ussing chamber, barrier function, surface area measurements, and gene expression. Net 22Na+ flux (JNET-Na; 80 kBq/15 mL), the rate and pathway of mucosal to serosal 3H-acetate (JMS-acetate; 37 kBq/15 mL) and 14C-butyrate (JMS-butyrate; 74 kBq/15 mL) flux, and serosal to mucosal flux of 3H-mannitol (JSM-mannitol; 74 KBq/15 mL) and tissue conductance were measured. Half of the chambers assigned to measure JMS-acetate and JMS-butyrate were further assigned to 1 of 2 acetate and butyrate concentration treatments: 10 mM (Low) and 50 mM (High). Furthermore, JSM-mannitol flux was also measured during an acidotic and hyperosmotic challenge (CHAL) and recovery (REC) to measure barrier function of ruminal tissue. Mean reticular pH, which was positively correlated with ruminal pH (R2 = 0.5477), decreased from 6.90 for CON to 6.59 for G7 then increased. Net Na+ flux increased 125% within 7 d. Total JMS-acetate and JMS-butyrate increased from CON to G21, where passive diffusion was the primary SCFA absorption pathway. Total JMS-acetate and JMS-butyrate were greater when incubated in High vs. Low. Effective surface area of the ruminal epithelium was not affected by dietary treatment. Increased JSM-mannitol, tissue conductance, and increased expression of IL-1β and TLR2 (tendencies) with increased days fed the moderate grain diet indicated reduced rumen epithelium barrier function. Furthermore, the CHAL treatment reduced barrier function, which was not reversible during REC. This study indicates that a moderate increase in diet fermentability increases rumen epithelium absorptive function in the absence of increased SA, but reduces barrier function. Data from this study also suggests that absorption and barrier function follow different timelines, posing a challenge for ruminant diet adaptation to moderately to highly fermentable diets.

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