The Method of Intraluminal Perfusion of the Human Small Intestine

Modigliani, R; Jc, Rambaud; Jj, Bernier

doi:10.1159/000197453

Cited by 27 publications

(21 citation statements)

References 42 publications

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“…The transmural PD and levels of net water and electrolyte transport during the control period were stable and similar to published values [8,9]. All subjects exhibited net water and Na absorption and a net K flux near zero.…”

Section: Water Und Electrolytr Trunsportsupporting

confidence: 84%

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Effects of acute respiratory acidosis on water and electrolyte transport in the human ileum

Eherer

Petritsch

Berger

et al. 1993

Eur J Clin Investigation

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Animal experiments have shown that acute respiratory acidosis stimulates water, Na and Cl absorption and HCO3 secretion in the ileum. The aim of this study was to investigate whether the human ileum also responds to changes in systemic acid-base balance. Seven healthy volunteers (mean age 24, range 21-29 years) underwent segmental ileal perfusion using a multi-lumen tube assembly with a proximal occluding balloon. A 30 cm test segment was perfused under steady state conditions with a plasma-like electrolyte solution containing PEG as a non-absorbable volume marker. After a control period, respiratory acidosis (blood pCO2 56.2 mmHg, pH 7.29 and [HCO3] 26.4 mmol l-1) was induced by CO2-breathing over a period of 50 min. Acute respiratory acidosis stimulated net HCO3 secretion in patients secreting HCO3 and reduced absorption in patients exhibiting net HCO3 absorption. These changes were immediate and appeared to be at least partly reversible. Net water, Na, K and Cl movement were not affected. The data suggest that HCO3 transport in the human ileum responds to acute respiratory acidosis.

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Section: Water Und Electrolytr Trunsportsupporting

confidence: 84%

“…Intestinal perfusion studies were performed as previously described [8,9,10]. Briefly, a quadruple-lumen tube assembly with an outer diameter of 5 mm with a proximal occluding balloon and a mercury bag at the tip was placed in the ileum.…”

Section: Intestinal Perfusionmentioning

confidence: 99%

Effects of acute respiratory acidosis on water and electrolyte transport in the human ileum

Eherer

Petritsch

Berger

et al. 1993

Eur J Clin Investigation

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“…However, the levels of glucose that actually reach the distal intestine are very low, 32 and glucose is therefore not likely to exert major effects on the L cell under physiological conditions. Similarly, although amino acids and peptones can also directly stimulate the L cell, 29,33 the majority of protein absorption by the GI tract occurs proximally 34 . In contrast, fatty acids reach the distal intestine at high levels, 35 and placement of fat into the ileum stimulates GLP release 10 .…”

Section: Regulation Of Glp‐1 and Glp‐2 Secretion By Nutrientsmentioning

confidence: 99%

The Glucagon‐Like Peptides

Brubaker

2006

Annals of the New York Academy of Sciences

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The glucagon-like peptides, GLP-1 and GLP-2, are cosecreted by intestinal L cells in response to nutrient ingestion. These peptides exert multiple effects on the gastrointestinal tract and pancreas to regulate the digestion, absorption, and assimilation of ingested nutrients, as well as providing feedback signals to the brain to modulate food intake. Tropic effects of GLP-1 and GLP-2 on their major peripheral target tissues, the beta cell and the intestinal epithelium, respectively, further enhance capacity for nutrient handling. When taken together, these findings demonstrate the diverse actions of the intestinal glucagon-like peptides to regulate nutrient homeostasis.

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“…For this computer simulation we have introduced values for parameters based as far as possible on data obtained in man. Thus the Real Km must be lower than our experimental Kms and is given a nominal value of 5 mM, the diffusion coefficient for glucose (D) is 9 45 x 10-6 cm-' s-', the range of unstirred layer thicknesses correspond to our own measurements, the real PDmax is ascribed a value of 10 mV and the Jmax is given a value of 4 nM/cm-2 s--', based upon the results of perfusion experiments in man (Modigliani et al, 1973). The values of Jmax from these experiments are expressed in terms of segment length and need to be converted to units of surface area for the computer simulation.…”

Section: Predictionsmentioning

confidence: 61%

“…and substituting values for Apparent Km and Jmax, obtained from absorption studies in which glucose absorption was estimated chemically (Modigliani et al, 1973). However, this method is unsatisfactory in practice for the following reasons: (1) Changes in PDmax are difficult to analyse because the relationship between the rate of glucose transfer (J) and the transfer PD is equivocal.…”

Section: Predictionsmentioning

confidence: 99%

Unstirred layer and kinetics of electrogenic glucose absorption in the human jejunum in situ

Read¹,

Barber²,

Levin³

et al. 1977

Gut

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SUMMARY Using an electrical technique we estimated the thickness of the unstirred layer in the human jejunum during kinetic studies of electrogenic glucose absorption. The unstirred layer in seven healthy volunteers (632 + 24 ,um: mean + SEM) was significantly thicker than in 10 patients with active coeliac disease (442 + 23 ,um) but not significantly different in seven patients who had responded to treatment by gluten withdrawal (585 + 49 ,um). There were similar differences in the values of 'Apparent Km' for electrogenic glucose absorption between healthy control subjects (36 + 6 mM) active coeliac patients (11 1 mM) and treated coeliac patients (31 + 5 mM). The changes in PDmax however, showed a different pattern. The PDmax in the active coeliac group (6f8 + 0 7 mV) was lower than in controls (7-6 + 0-6 mV) but not significantly so, while the PDmax in the treated coeliac group (10-6 + 0 9 mV) was significantly higher than in both the active coeliac and control groups. It should be noted that both operational kinetic parameters obtained in the present study are much lower than those obtained previously (Read et al., 1976b) because of the use of siphonage. Analysis of the results using a computer simulation indicates that the reduction in Apparent Km in active coeliac disease can be caused by the interaction of the decreased maximal absorption rate for glucose (Jmax) with the attenuated unstirred layer. In these circumstances it is not necessary to postulate any change in the affinity of the transport mechanism for glucose ('Real Km'). It is remarkable that the disease process produces an Apparent Km which is much closer to the Real Km than that found in health.Part 1: Measurement of functional unstirred layer thicknessWe have previously described a technique for measuring changes in transmural potential difference (PD) across the human jejunum in vivo in response to infusion of solutions containing glucose (Read et al., 1974). Using this technique we observed that the operational kinetic parameters ('Apparent Km', PDmax) for the active electrogenic component of glucose absorption were significantly lower in untreated coeliac disease than in healthy controls (Read et al., 1976b). It is possible that these results could be caused by differences in the thickness of the layer of unstirred fluid which lies adjacent to the mucosal epithelium.In this present paper we used an electrical technique for estimating the thickness of this unstirred

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The Method of Intraluminal Perfusion of the Human Small Intestine

Cited by 27 publications

References 42 publications

Effects of acute respiratory acidosis on water and electrolyte transport in the human ileum

Effects of acute respiratory acidosis on water and electrolyte transport in the human ileum

The Glucagon‐Like Peptides

Unstirred layer and kinetics of electrogenic glucose absorption in the human jejunum in situ

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