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R A Argenzio

Publications and source records attributed to R A Argenzio.

5 recordsLinked to original sources
PubMed1979

Inter-relationship of sodium, chloride, bicarbonate and acetate transport by the colon of the pig.

1. Net transport of Na, Cl, HCO3 and acetate was examined in the temporarily isolated colon of conscious pigs weighing 46 +/- 8 kg. 2. The entire colon absorbs 4.1 ml. H2O, 0.8 m-equiv Na, 1.3 m-equiv acetate and secretes 0.5 m-equiv HCO3/min with a solution comparable to the normal contents. The absorptive capacity of the proximal and distal halves of the colon was comparable per unit dry weight of mucosa when each segment was presented with the same solution. 3. A series of studies using ion replacement solutions showed that net Na absorption and net HCO3 accumulation in the lumen solution were both increased in the presence of acetate. Cl absorption was independent of Na absorption and was accompanied by an equivalent net secretion of HCO3 in the absence of Na. When NaCl in the perfusion solution was replaced with Na2SO4, Na and HCO3 were absorbed at equal rates. 4. Final pCO2 values observed in NaCl and Na2SO4 solutions were greater than those observed in plasma while the pCO2 of the Na acetate solution after perfusion was reduced to values below plasma concentrations. 5. Results are consistent with the hypothesis that hydration of CO2 in the lumen solution or mucosal cell provides a continuous source of H ions for absorption of the more permeable undissociated acid. The evidence also suggests an additional source of H ions may be provided by a Na-H exchange process located in one of the limiting cell membranes.

Acetates↗
PubMed1975

Sites of organic acid production and absorption in gastrointestinal tract of the pig.

The relationship between diet, pH, and microbial digestion of carbohydrate was examined in 24 pigs fed either a conventional or a low-protein, high-cellulose experimental diet and sacrificed 2, 4, 8, or 12 h after a meal. In animals fed the control diet contents of the cranial half of the stomach demonstrated marked, cyclic fluctuations in pH and high concentrations of organic acids. Contents of the caudal (glandular) half were lower in both pH and organic acid concentration. Despite concentrations of volatile fatty acids (VFAs) as high as 250 meq/liter in the large intestine, the pH remained relatively neutral. The VFA levels remained relatively constant throughout the length of the colon. The VFA transport across isolated gastric and large intestinal mucosa also was examined. All four types of gastric mucosa absorbed and transported VFA at substantial rates. Mucosa of pig cecum and colon transported VFA at much greater rates than gastric mucosa and greater rates than previously determined in equine large intestinal mucosa or even bovine rumen epithelium. Comparison with results of earlier studies in the pony suggested that the higher concentration of VFA in the large intestinal contents of pigs was due to the more rapid rate of digesta passage rather than to less efficient absorption of fatty acids.

Animals↗
PubMed1975

Effect of volatile fatty acids on water and ion absorption from the goat colon.

The absorption of volatile fatty acids (VFA) and the influence of VFA on the net transport of inorganic electrolytes and water were examined in the temporarily isolated colon of the conscious goat. Perfusion of the colon with a solution similar in content to that normally present in the cecal outflow showed that the net absorption of VFA was more rapid than that of any other ion present in the solution. When the VFA were replaced with Cl, the net absorption of Na and water was reduced nearly twofold. Increasing the pH of the solution from 6.0 to 7.4 in the presence of VFA also resulted in a twofold decreased in the net transport of Na and water. Perfusion of the colon with a hypertonic solution resulted in approximately zero net water transport; however, the net absorption of Na and VFA continued at similar rates as before. These results support the concept that the colon primarily conserves solute followed by the passive movement of water. They also demonstrate that VFA are rapidly absorbed from the goat colon and indicate a striking influence of VFA on the net transport of Na and water. The presence of VFA in the large intestine may be important for normal absorptive function.

Animals↗