The Relation between Faecal pH, Ammonia, and Bicarbonate in Man

Pf, Down; Agostini, Lucas; Murison, J.; Om, Wrong

doi:10.1042/cs042024pa

Cited by 4 publications

(1 citation statement)

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“…The rate of dialysis in the lower colon and rectum might be considerably delayed due to poor mixing; this would allow the accumulation of bacterial metabolites such as short-chain fatty acids and ammonia in the stool fluid. Down et al (1972) have provided evidence that an increase in the acidity of the medium will retard ammonia absorption.…”

Section: Discussionmentioning

confidence: 99%

A comparison of stool fluid and stool dialysate obtained in vivo

Tarlow¹,

Thom²

1974

Gut

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SUMMARY Stool fluid has been obtained for analysis by homogenization and high speed centrifugation of fresh stool.This fluid, from two healthy individuals with soft stools has been compared with stool dialysate obtained in vivo by retrieval of swallowed dialysis bags from their stools. Stool fluid was more acid, with a higher osmolality, an increased concentration of organic anions, sugar and ammonia, and a lower bicarbonate concentration than dialysate in vivo. It is suggested that in the individuals studied, dialysate in vivo may not be in equilibrium with the stool fluid surrounding it, and may not represent a true dialysate of faecal water.The investigation of the composition of stool poses a number of difficult problems. Stool is a multiphasic system containing solid material, colloidal solutions of both sol and gel varieties and true crystalloid solutions. The solutes in true solution within the stool may be sequestered into two or more separate compartments.Early techniques for the investigation of the composition of stool involved acid digestion or ashing, with subsequent chemical analysis. These techniques are obviously of limited applicability, they do not differentiate between material in solid or liquid phases of stool, and can only be applied to minerals resistant to these drastic physical or chemical techniques.In 1961, an elegant technique for dialysis in vivo of stool was introduced by Wrong and his coworkers (Wrong, Morrison, and Hurst, 1961). This involved subjects swallowing bags made of cellulose acetate dialysis tubing, closed at both ends and containing a small amount of an oncotic agent. These bags were recovered from the stool, and it was assumed that the contents represented 'the extracellular component of faecal water'. Slyke and Neill (1924); organic anions by a modification of the method of Van Slyke and Palmer (1920) using a pH meter and microelectrode; total sugar by a modification of the copper reduction technique described by Somogyi (1952); individual sugars by semiquantitative thin-layer chromatography on silica gel (Baron and Economidis, 1963); total stool water by drying a homogenized aliquot to constant weight at 100°C; and osmolality by freezing-point depression using an Advanced osmometer.

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Section: Discussionmentioning

confidence: 99%