The correlation of ethanol-induced depression of glucose and water transport with morphological changes in the hamster jejunum in vivo

1978 ◽  
Vol 56 (1) ◽  
pp. 123-131 ◽  
Author(s):  
J. E. Fox ◽  
T. F. McElligott ◽  
I. T. Beck

Glucose and water transport is depressed in the hamster jejunum in vivo by ethanol (4.8%) which also produced fluid-filled blebs at the tips of the villi. The epithelial cells over the blebs appeared stretched and cuboidal, the lateral intercellular spaces (LIS) were no longer recognizable, and the lacteals were closed. Forty-five minutes after discontinuation of the ethanol, water transport returned to normal while glucose transport remained depressed. At this time the villus structure had returned to normal. The blebs had disappeared, the LIS were again recognizable, and their appearance and number were similar to those in the control animals. Thus, the depression of water transport correlated with the obvious structural changes caused by ethanol; however, the depression of glucose absorption is associated with some effect of ethanol not evident by routine light microscopy.

1975 ◽  
Vol 53 (3) ◽  
pp. 439-450 ◽  
Author(s):  
T. F. McElligott ◽  
I. T. Beck ◽  
P. K. Dinda ◽  
S. Thompson

Experiments were done for identification and localization of certain structural changes at different levels of jejunal villus of the hamster during positive and negative water transport across the intestine in vivo and in vitro. Positive transport occurred when the mucosal surface of the intestine was bathed (in vitro experiments) or perfused (in vivo experiments) with isotonic Krebs–Ringer bicarbonate solution containing 10 mM glucose, and negative water transport was achieved by rendering this solution hypertonic with 150 mM mannitol. Results indicate that during positive net water transport, the intestine in vivo transported more fluid and exhibited a more conspicuous dilatation of the lateral intercellular spaces (L.I.S.) than did the in vitro preparation. Dilatation of the L.I.S. in both preparations was present only in the apical part of the villus, suggesting that this is the principal site of water absorption. When the mucosal solution was made hypertonic with mannitol, the L.I.S. in the in vivo intestine totally collapsed, whereas in the in vitro intestine these spaces remained open very slightly. These morphological changes correspond well with our finding that in the presence of the hypertonic mucosal solution there was a greater net negative water transport in vivo than in vitro. Incubation of the intestine in the isotonic mucosal solution produced subnuclear swelling of the mid-villus epithelial cells, and this morphological change was associated with an increase in the water content of the tissue. Perfusion of the in vivo intestine with the isotonic solution produced neither the swellings nor the increase in water content of the tissue. In the presence of hypertonic mucosal solution there was a water loss from the tissue both in vivo and in vitro, and these swellings were not observed. These results are discussed in relation to intestinal sugar transport and to the maturity of the epithelial cells, and it is concluded that transport studies on in vitro preparations may provide valid information on a qualitative basis, if not on a strictly quantitative basis.


2007 ◽  
Vol 19 (1) ◽  
pp. 15-22 ◽  
Author(s):  
Balaji B. Maruthi Sridhar ◽  
Fengxiang X. Han ◽  
Susan V. Diehl ◽  
David L. Monts ◽  
Yi Su

The objectives of this study were to identify the structural changes caused by Zn and Cd accumulation in shoots and roots of barley (Hordeum vulgare) plants; and to correlate metal accumulation with anatomical, physiological and morphological changes. Potted plants were exposed to metal treatments of Zn and Cd for 19 and 16 d respectively. Leaves, stems and roots were harvested to identify structural changes and analyze metal accumulation. Barley effectively accumulated Zn (up to 11283 mg kg-1) and Cd (up to 584 mg kg-1) in the shoots. Microscopic structural changes, such as a decrease in intercellular spaces, breakdown of vascular bundles, and shrinkage of palisade and epidermal cells, occurred in leaves, stems and roots of plants treated with high concentrations of Zn. Zinc accumulation also resulted in a significant decrease in water content, fresh weight, dry weight and plant height. Cadmium only caused structural changes in roots at the higher concentrations. Barley plants were able to accumulate significant amounts of Zn and Cd without exhibiting symptoms of phytotoxicity when the metal concentrations were relatively low.


2020 ◽  
pp. 23-27
Author(s):  
В. В. Елагин ◽  
Д. А. Костина ◽  
О. И. Братчиков ◽  
Т. Г. Покровская ◽  
С. Л. Кузнецов ◽  
...  

Цель - выявить и изучить степень выраженности морфологических изменений структур коркового и мозгового вещества почки на фоне смоделированной билатеральной модели ишемии-реперфузии. Материал и методы. Эксперименты проведены на 50 крысах-самцах линии Вистар массой 180-220 г. Моделирование билатеральной модели ишемии-реперфузии проводилось путем наложения атравматичных зажимов на обе почечные ножки на 40 мин. Через 24 или 72 ч реперфузии проводили оценку выраженности структурных изменений в корковом и мозговом веществе почки с использованием гистологических и морфометрических методик. Измеряли высоту эпителиоцитов в проксимальном и дистальном извитых канальцах нефрона, площадь поперечного сечения почечного тельца, клубочка и капсулярного пространства. Результаты. Полученные морфологические изменения в виде нарушения структурности эпителия как в корковом, так и в мозговом веществе почки на 1-е сутки эксперимента имеют тенденцию к увеличению степени их выраженности. К 3-м суткам эксперимента наиболее выраженные реактивно-деструктивные изменения визуализируются в реабсорбционносекреторных отделах нефрона, которые проявляются в виде снижения высоты эпителиоцитов проксимальных и дистальных канальцев, отслоением их от базальной мембраны и слущиванием. Усугубление схожей морфологической картины происходило в собирательных трубках, в просветах которых определялись конгломераты из отслоившихся от базальной мембраны погибших клеток эпителия. Выявленные реактивно-деструктивные изменения в почках морфологически обосновывают адекватность создания модели ишемии-реперфузии. Выводы. 40-минутная билатеральная ишемия почек с последующей реперфузией в течение 1-3 сут приводит к выраженным структурным изменениям в почках, что соответствует характеристике острого почечного повреждения. Objective - to identify and study the severity of morphological changes in the structures of the renal cortex and medulla in the bilateral model of ischemia-reperfusion. Material and methods. The experiments were performed on 50 male Wistar rats weighing 180-220 grams. A bilateral ischemia-reperfusion was modelled by applying atraumatic clamps to both kidney pedicles for 40 minutes. After 24 or 72 hours of reperfusion, the severity of structural changes in the renal cortex and medulla was assessed using histological and morphometric techniques. The height of epithelial cells in the proximal and distal convoluted tubules of the nephron, the cross-sectional area of the renal corpuscle, glomerulus and capsular space were measured. Results. Severe structural changes in the renal tissue affecting both the tubular and glomerular apparatus of the kidneys were found, with the increase in pathological changes from the first to the third days of the experiment in the form of a decrease in the epithelial height of the distal and proximal tubules, as well as a decrease in the area of the renal corpuscle and vascular glomerulus. The morphological changes in the form of a structural damage of the epithelium of both renal cortex and medulla were detected on the 1st day of the experiment, and they tend to increase their severity. By the 3rd day of the experiment, the most pronounced reactive-destructive changes were visualized in the reabsorption-secretory sections of the nephron. They were manifested as a decrease in the height of the proximal and distal tubule epithelial cells, their exfoliation from the basement membrane and desquamation. The similar but more aggravated morphological picture was seen in collecting tubes, where conglomerates of dead epithelial cells exfoliated from the basement membrane were found in the gaps. The revealed reactive-destructive changes in the kidneys morphologically substantiate the adequacy of creating a model of ischemia-reperfusion. Conclusions. A 40-minute bilateral renal ischemia followed by reperfusion leads to severe structural changes in the kidneys in 1-3 days, which corresponds to a characteristic of acute renal damage.


2002 ◽  
Vol 115 (4) ◽  
pp. 713-724
Author(s):  
Isabelle Runembert ◽  
Guillaume Queffeulou ◽  
Pierre Federici ◽  
François Vrtovsnik ◽  
Emma Colucci-Guyon ◽  
...  

It has been reported that vimentin, a cytoskeleton filament that is expressed only in mesenchymal cells after birth, is re-expressed in epithelial cells in vivo under pathological conditions and in vitro in primary culture. Whether vimentin re-expression is only a marker of cellular dedifferentiation or is instrumental in the maintenance of cell structure and/or function is a matter of debate. To address this issue, we used renal proximal tubular cells in primary culture from vimentin-null mice (Vim-/-) and from wild-type littermates (Vim+/+). The absence of vimentin did not affect cell morphology, proliferation and activity of hydrolases, but dramatically decreased Na-glucose cotransport activity. This phenotype was associated with a specific reduction of SGLT1 protein in the detergent-resistant membrane microdomains (DRM). In Vim+/+cells, disruption of these microdomains by methyl-β-cyclodextrin decreased SGLT1 protein abundance in DRM, a change that was paralleled by a decrease of Na-glucose transport activity. Importantly, we showed that vimentin is located to DRM, but it disappeared after methyl-β-cyclodextrin treatment. In Vim-/- cells,supplementation of cholesterol with cholesterol-methyl-β-cyclodextrin complexes completely restored Na-glucose transport activity. Interestingly,neither cholesterol content nor cholesterol metabolism changed in Vim-/- cells. Our results are consistent with the view that re-expression of vimentin in epithelial cells could be instrumental to maintain the physical state of rafts and, thus, the function of DRM-associated proteins.


2002 ◽  
Vol 70 (4) ◽  
pp. 2198-2205 ◽  
Author(s):  
B. I. Kazmierczak ◽  
J. N. Engel

ABSTRACT The Pseudomonas aeruginosa protein ExoT is a bacterial GTPase-activating protein (GAP) that has in vitro activity toward Rho, Rac, and Cdc42 GTPases. Expression of ExoT both inhibits the internalization of strain PA103 by macrophages and epithelial cells and is associated with morphological changes (cell rounding and detachment) of infected cells. We find that expression of ExoT leads to the loss of GTP-bound RhoA, Rac1, and Cdc42 in transfected HeLa cells, demonstrating that ExoT has GAP activity in vivo toward all three GTPases. GAP activity is absolutely dependent on the presence of arginine at position 149 but is not affected by whether ExoT is expressed in the absence or presence of other P. aeruginosa type III secreted proteins. We also demonstrate that expression of ExoT in epithelial cells is sufficient to cause stress fiber disassembly by means of ExoT's GAP activity toward RhoA.


1968 ◽  
Vol 36 (2) ◽  
pp. 355-367 ◽  
Author(s):  
Charles E. Ganote ◽  
Jared J. Grantham ◽  
Harold L. Moses ◽  
Maurice B. Burg ◽  
Jack Orloff

Isolated cortical collecting tubules from rabbit kidney were studied during perfusion with solutions made either isotonic or hypotonic to the external bathing medium. Examination of living tubules revealed a reversible increase in thickness of the cellular layer, prominence of lateral cell membranes, and formation of intracellular vacuoles during periods of vasopressin-induced osmotic water transport. Examination in the electron microscope revealed that vasopressin induced no changes in cell structure in collecting tubules in the absence of an osmotic difference and significant bulk water flow across the tubule wall. In contrast, tubules fixed during vasopressin-induced periods of high osmotic water transport showed prominent dilatation of lateral intercellular spaces, bulging of apical cell membranes into the tubular lumen, and formation of intracellular vacuoles. It is concluded that the ultrastructural changes are secondary to transepithelial bulk water flow and not to a direct effect of vasopressin on the cells, and that vasopressin induces osmotic flow by increasing water permeability of the luminal cell membrane. The lateral intercellular spaces may be part of the pathway for osmotically induced transepithelial bulk water flow.


2020 ◽  
Vol 319 (1) ◽  
pp. L11-L20 ◽  
Author(s):  
Denise Stanford ◽  
Harrison Kim ◽  
Sandeep Bodduluri ◽  
Jennifer LaFontaine ◽  
Stephen A. Byzek ◽  
...  

Structural changes to airway morphology, such as increased bronchial wall thickness (BWT) and airway wall area, are cardinal features of chronic obstructive pulmonary disease (COPD). Ferrets are a recently established animal model uniquely exhibiting similar clinical and pathological characteristics of COPD as humans, including chronic bronchitis. Our objective was to develop a microcomputed tomography (µCT) method for evaluating structural changes to the airways in ferrets and assess whether the effects of smoking induce changes consistent with chronic bronchitis in humans. Ferrets were exposed to mainstream cigarette smoke or air control twice daily for 6 mo. µCT was conducted in vivo at 6 mo; a longitudinal cohort was imaged monthly. Manual measurements of BWT, luminal diameter (LD), and BWT-to-LD ratio (BWT/LD) were conducted and confirmed by a semiautomated algorithm. The square root of bronchial wall area (√WA) versus luminal perimeter was determined on an individual ferret basis. Smoke-exposed ferrets reproducibly demonstrated 34% increased BWT ( P < 0.001) along with increased LD and BWT/LD versus air controls. Regression indicated that the effect of smoking on BWT persisted despite controlling for covariates. Semiautomated measurements replicated findings. √WA for the theoretical median airway luminal perimeter of 4 mm (Pi4) was elevated 4.4% in smoke-exposed ferrets ( P = 0.015). Increased BWT and Pi4 developed steadily over time. µCT-based airway measurements in ferrets are feasible and reproducible. Smoke-exposed ferrets develop increased BWT and Pi4, changes similar to humans with chronic bronchitis. µCT can be used as a significant translational platform to measure dynamic airway morphological changes.


1967 ◽  
Vol 50 (5) ◽  
pp. 1173-1182 ◽  
Author(s):  
Alan K. Rider ◽  
Harold P. Schedl ◽  
George Nokes ◽  
Streeter Shining

Proximal and distal small intestinal segments of the rat were perfused in situ at two different rates with isotonic solutions containing glucose in concentrations ranging from 25 to 600 mg/100 ml. Absorption was measured as glucose disappearance rate from the lumen. Glucose absorption had not previously been studied at intraluminal concentrations above and below blood glucose. Absorption was more rapid from the proximal segment. In both segments absorption was independent of perfusion rate and of whether glucose was analyzed by counting 14C or by the Somogyi method. The latter finding suggests that of the unidirectional fluxes, flux out of the bowel is much greater than flux into the bowel. In contrast to the findings in previous studies neither segment showed rate-limiting kinetics, and the Michaelis-Menten analysis was not applicable. The form of the curve depicting absorption rate in relation to concentration differed between the two segments. At the higher concentrations absorption rate continued to increase much more rapidly in the proximal than in the distal segment. The observations could not be explained by known mechanisms of glucose transport and illustrate the difficulties of achieving biochemically and physiologically meaningful in vivo studies of intestinal absorption.


1967 ◽  
Vol 2 (1) ◽  
pp. 89-112 ◽  
Author(s):  
M. J. BERRIDGE ◽  
B. L. GUPTA

The fine structure of the epithelial cells of the rectal papillae in the blowfly, Calliphora erythrocephala Meig., has been investigated to elucidate the possible mechanism of reabsorption of water and ions from the rectal lumen. To observe the variations in the structure of the epithelium in response to the absorptive processes the material was taken (a) from flies at the various stages of their first oviposition cycle, and (b) from freshly emerged imagoes starved for 2 days and injected into the rectum with solutions of various tonicities. It has been found that the complex system of intercellular spaces, formed by a prolific infolding of the lateral plasma membrane of the cells, shows a direct response to the conditions of supposedly maximal and minimal transport of fluid. These spaces are (a) grossly distended in the flies injected with hypotonic media, (b) highly dilated under normal conditions, and (c) completely collapsed in fasting and starved flies. These observations have been discussed in the light of the available theories to explain the mechanism of water transport in biological tissues. It is proposed that the structural design of the rectal papillae favours the application of double-membrane theory to explain the reabsorption of water against osmotic gradients as a consequence of an active transport of solutes into enclosed spaces.


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