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Biomedical subjects

W E Roe

Publications and source records attributed to W E Roe.

11 recordsLinked to original sources
PubMed1979

Permeability properties of swine small intestine: effect of a heat stable Escherichia coli enterotoxin.

The permeability of weanling swine small intestine was estimated using measurements of filtration coefficients and equivalent pore size. Hypertonic solutions of mannitol, erythritol and urea were used to calculate reflection coefficients in the duodenum, mid jejunum and distal jejunum. Estimated effective pore radius was 6.4-7.4, 5.6-7.2 and 4.7-4.9A degrees in the three respective regions. Similarly the filtration coefficient induced by hypertonic solutions of mannitol decreased significantly in the distal jejunal segments. The results show an aboral gradient of decreasing permeability along the small intestine of the weanling pig. In situ incubation of loops in the proximal jejunum with a heat stable Escherichia coli enterotoxin for one hour did not significantly change the effective pore size as calculated from reflection coefficients of hypertonic solutions of erythritol and urea. However, the filtration coefficients of loops exposed to the enterotoxin were significantly greater than control loops with hypertonic solutions of erythritol and urea but not mannitol. This suggests the occurrence of a slight reduction in epithelial porosity. The results support the hypothesis that intestinal secretion induced by heat stable E. coli enterotoxin is not the result of an increased mucosal permeability.

Animals↗
PubMed1978

The effect of cholera toxin and heat labile and heat stable Escherichia coli enterotoxin on cyclic AMP concentrations in small intestinal mucosa of pig and rabbit.

The effect of cholera toxin, heat labile and heat stable Escherichia coli enterotoxin on mucosal cyclic AMP concentrations was determined on the proximal jejunum of weanling pigs and young rabbits. Ligated loops were injected with solutions containing no enterotoxin for control and either cholera toxin, heat labile or heat stable E. coli enterotoxin. The loops were drained after either two, four or six hours incubation at which time accumulated fluid was recorded and mucosal samples removed for determination of cyclic AMP concentration. In the rabbit, cholera toxin and heat labile, but not heat stable E. coli enterotoxin stimulated intestinal secretion while in the pig all three enterotoxins induced net fluid accumulation. Cholera toxin and heat labile, but not heat stable E. coli enterotoxin elevated rabbit mucosal cyclic AMP concentrations. In the pig these enterotoxins had no significant effect on mucosal cyclic AMP concentrations. The results are inconsistent with the hypothesis that the adenyl cyclase system is an essential step for enterotoxin induced intestinal secretion. The activation of intestinal adenyl cyclase by bacterial enterotoxins may only be an associated and not a necessary event for the stimulation of intestinal secretion.

Animals↗
PubMed1978

Effects of intraluminal glucose on intestinal secretion induced by heat stable and heat labile Escherichia coli enterotoxin, cholera toxin and theophylline.

Glucose, l-alanine, l-aspartate, l-methionine and glycine enhanced net fluid and electrolyte absorption in acute isolated loops of the proximal jejunum of weanling swine. The effect of glucose on intestinal secretion induced by heat stable and heat labile Escherichia coli entero-toxin, cholera toxin and theophylline was examined in both the proximal and distal jejunum of weanling swine. In the proximal jejunum glucose enhanced the rate of net fluid and electrolyte absorption. This increase was accompanied by an increase in unidirectional dosium absorption. In loops exposed to either heat stable or heat labile enterotoxins, glucose significantly decreased the rate of net fluid and electrolyte secretion. The magnitude of glucose enhancement in loops exposed to heat stable and heat labile enterotoxins was similar to adjacent control loops. However, glucose enhancement did not occur in loops exposed previously to cholera toxin or concurrently to theophylline. Therefore, cholera toxin and theophylline may inhibit substrate dependent sodium absorption in the proximal jejunum. In the distal jejunum glucose enhancement did occur but the rate of enhancement was less than in the proximal jejunum. In this region glucose enhancement was not evident in loops exposed to either theophylline, heat stable, heat labile or cholera toxin.

Amino Acids↗
PubMed1978

Effect of heat stable and heat labile Escherichia coli enterotoxins and cholera toxin in combination with theophylline on unidirectional sodium and chloride flux in the small intestine of weanling swine.

The effect of heat stable and heat labile Escherichia coli enterotoxins or cholera toxin in combination with theophylline on net water, sodium and chloride and unidirectional sodium and chloride fluxes was examined in acute isolated loops of jejunum of weanling swine. The effect of heat stable enterotoxin in combination with theophylline was determined in loops located in the proximal jejunum, while combinations of theophylline and either heat labile enterotoxin or cholera toxin were studied in the distal jejunum. In each situation the addition of theophylline resulted in an additive rather than a synergistic increment of intestinal secretory activity. This study implies that the intestinal adenyl cyclase system and enterotoxin induced intestinal secretion may not be directly related in the swine small intestine.

Animals↗
PubMed1977

Electrolyte levels and net fluid and electrolyte movements in the gastrointestinal tract of weanling swine.

Electrolyte concentrations, osmolality and pH were determined in conventionally raised weanling swine fed a liquid diet. Incorporation of a dilution marker into the diet in combination with frequent feeding enabled estimations as to the sites of relative fluid and electrolyte absorption and secretion along the gastrointestinal tract. Unlike many other species the weanling pig depends largely on its large intestine for absorption of fluid and electrolytes with small changes in net fluid movement occurring along the jejunal and ileal segments. Additional observations included the absorption of water by the porcine stomach which increased dilution marker concentration by approximately twofold and the high osmolality values recorded in the small and large intestine. The implications of these observations are discussed with regard to pathogenesis of colibacillary diarrhea in the weanling pig.

Animals↗
PubMed1977

Effect of heat stable and heat labile Escherichia coli enterotoxins, cholera toxin and theophylline on unidirectional sodium and chloride fluxes in the proximal and distal jejunum of weanling swine.

Acute, isolated loops of proximal and distal jejunum of weanling swine were exposed to either heat stable porcine Escherichia coli enterotoxin, heat labile porcine Escherichia coli enterotoxin, cholera toxin or theophylline. Unidirectional sodium fluxes in response to heat stable in the proximal jejunum were dependent on the length of time that the intestinal mucosae was exposed to the enterotoxin. Net water, sodium and chloride and unidirectional sodium and chloride flux measurements in the proximal jejunum in response to each agent uniformly indicated that net secretion of fluid and electrolytes was the result of increased unidirectional sodium secretion or blood-to-lumen flux and decreased unidirectional chloride absorption or lumen-to-blood flux. In addition heat stable cholera toxin and theophylline but not heat labile decreased unidirectional chloride secretion a small but significant amount in the proximal jejunum. Sodium and chloride flux measurements in the distal jejunum demonstrated that all four secretory agents could stimulate net secretion of water, sodium and chloride in that region. The response to these secretory agents as measured by sodium and chloride unidirectional flux rates was not similar to changes observed in the proximal jejunum. In the distal small intestine, whereas heat labile cholera toxin and theophylline induced similar qualitative changes in unidirectional sodium and chloride fluxes, that induced by heat stable differed.

Animals↗
PubMed1974

Experimental edema disease of swine (E. coli enterotoxemia). II. The development of hypertension after the intravenous administration of edema disease principle.

The intravenous inoculation of edema disease principle induced profound hypertension in pigs. The increase in blood pressure occurred approximately 40 hours after inoculation and coincided with the development of the characteristic neurological disturbance of edema disease. Therefore hypertension may play a pathogenetic role in the neuropathy of experimental edema disease.

Animals↗
PubMed1970

Effect of enteropathogenic Escherichia coli infection on the transmembrane potential of the swine intestine.

Transmural potential difference and short-circuit current were measured on membranes of swine small intestine as an index of transport activity for sodium ion. The measurements were made in vitro on membranes prepared from control and E. coli 0138-infected intestinal loops from weanling pigs. Measurements were made on duodenal and upper, middle and lower jejunal segments. No differences were noted in the transmembrane potential difference and the short-circuit current between the control and the experimentally infected loops.

Animals↗