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At least 19 recordsLinked to original sources
PubMed1978

Vitamin D-3 intestinal absorption in vivo: influence of fatty acids, bile salts, and perfusate pH on absorption.

Intestinal absorption of vitamin D-3 in physiological concentrations was studied in the live unanesthetised rat. In both the jejunum and the ileum a linear relationship was found between the absorption rate of the vitamin and its intraluminal concentration. Increasing the sodium taurocholate concentation in the perfusate above 5mM did not change ileal absorption rate but did decrease jejunal absorption rate. The vitamin's rate of absorption was raised by increases in either the hydrogen ion concentration in vivo is mediated by passive diffusion. The rate of absorption of ttion or the perfusate's flow rate. Addition of 2.5 mM fatty acids of varying chain length and degrees of saturation resulted in a decrease in the rate of vitamin D-3 absorption. These experiments indicate that vitamin D-3 absorption in vivo is mediated by passive diffusion. The rate of absorption of the vitamin is influenced by the composition of the perfusate and the thickness of the unstirred layer.

Animals↗
PubMed1976

Effects of haemodialysis on fractional intestinal absorption of calcium in uraemia.

Fractional intestinal absorption of calcium was measured in 41 haemodialysed patients 4 hours after an oral dose of 47 Ca. Fractional intestinal calcium absorption was 40.3 +/- 1.9% (SEM) when measured 10 to 12 hours after a haemodialysis session (dialysate calcium concentration: 1.75 mmol/litre). This value was significantly lower (p less than 0.001) than that in 26 healthy controls (56.8 +/- 1.8%) and higher (p less than 0.05) than that of 35 patients with chronic renal failure treated conservatively (34.5 +/- 2.1%). In 17 patients, fractional intestinal calcium absorption was measured just before and just after a dialysis session. Pre-dialysis fractional intestinal calcium absorption (33.7 +/- 3.0%) was not significantly different from fractional intestinal calcium absorption in uraemic patients treated conservatively, while after dialysis fractional intestinal calcium absorption had increased significantly to 42.0 +/- 2.6% (p less than 0.001). It is suggested that the transient increase in fractional intestinal calcium absorption observed after dialysis could be related to dialysis induced volume depletion rather than to a vitamin D-dependent mechanism.

Calcium↗
PubMed1976

A review of laboratory tests of intestinal absorption in the tropics.

The intestinal absorptive capacity for xylose and folic acid has frequently been found to be defective in apparently normal asymptomatic residents of the tropics. This suggests the presence among the natives of the tropics of appreciable, yet asymptomatic jejunal functional incompetence which is not seen in the temperate countries. Further, structural abnormalities in the villi which are non-specific occur in varying degrees of severity in the tropics both in health and in disease. These tropical peculiarities raise obvious doubts as to the diagnostic usefulness of these laboratory tests in the evaluation of disorders of absorption in tropical practice. In this review, experiences from the Lagos University Teaching Hospital had shown that the faecal fat analysis for the detection of steatorrhoea is the most dependable single diagnostic and in studies of overt malabsorption in Niageria.

Feces↗
PubMed1977

Fetal bile salt metabolism. The intestinal absorption of bile salt.

The intestinal absorption of sodium taurocholate was studied in the near-term fetal and neonatal dog. Absorption rates were measured in vivo in isolated loops of fetal jejunum and ileum. Absorption was also measured in vitro in everted sacs and rings of fetal and neonatal jejunum and ileum. The maximal rates of taurocholate absorption observed after instillation of 1 micronmol taurocholate into closed segments of fetal jejunum and ileum with intact blood supply were not significantly different (P less than 0.2), and equalled 0.282+/-0.026 (mean+/-SEM) and 0.347+/-0.051 micronmol/h per 10-cm segment length jejunum and ileum, respectively. Similarly, the rates of absorption from open segments of jejunum and ileum perfused with 0.4 and 1.0 mM taurocholate were nearly identical (0.232+/-0.040 and 0.255+/-0.039, respectively at 0.4 mM, and 0.470+/-0.065 and 0.431+/-0.013, respectively at 1.0 mm) (P greater than 0.2). At perfusate concentrations of 4.0 mM, moreoever, jejunal absorption exceeded ileal absorption (1.490+/-0.140 and 0.922+/-0.200, respectively (P less than 0.05). As expected, concentration of taurocholate by the mucosa was readily demonstrated in adult ileal, but not in adult jejunal everted rings. In contrast, there were no significant differences in mucosal uptake of taurocholate by fetal jejunal and ileal rings. Fetal ileal mucosal concentrations were not significantly above those in the incubation medium after 1-h exposure of the mucosa to 0.003, 0.03, and 0.3 mM taurocholate. Uptake was proportional to incubation medium concentration over the full range of values. This was also true of tissues from 1-wk-old neonates. However, by 2 wk of age, ileal mucosal concentration of taurocholate was evident and adult levels were attained by 5 wk of age. It is concluded that taurocholate is absorbed by the fetal gut and that ileal absorption is no more efficient than jejunal absorption. Although active glucose transport was demonstrable in both jejunum and ileum, it was not possible to demonstrate an ileal mechanism for active transport of taurocholate in the fetus. Active ileal transport was not demonstrable in the newborn until at least 2 wk after birth.

Age Factors↗
PubMed1976

Type I hyperprolinemia: a study of the intestinal absorption of proline, hydroxyproline, and glycine.

Intestinal absorption of proline, hydroxyproline, and glycine was interpreted by investigation of a type I hyperprolinemia patient and six control subjects. Intestinal perfusion was performed. When proline (Pro), hydroxyproline (OH-Pro), and glycine (Gly) were infused together, an increase in proline concentration did not alter aminoacid uptake in the control subjects; however, in the hyperprolinemia patient, uptake of aminoacids became negliglible (Pro, 17--6 muM/min; OH-Pro, 15--0.3 muM/min; and Gly, 13.5--0 muM/min). When each aminoacid was infused alone at increasing concentrations aminoacid uptake increased in controls; in the hyperprolinemic patient, intestinal absorption was less for glycine and hydroxyproline but aminoacid uptake increased with substrate concentration; however, for proline, the uptake remained constant (1l.5--17 muM/min/20 cm of intestinal test segment) (Table 1). When hydroxyproline was infused with an increased concentration of proline in the hyperprolinemic patient, hydroxyproline uptake first increased (9.8--14.3 muM/min/20 cm) then decreased to its basal value, whereas, in the control subjects, uptake increased without decreasing subsequently.

Biological Transport↗
PubMed1979

[Postoperative intestinal absorption in old age (author's transl)].

The function of intestinal absorption was analysed in elderly patients before and after cholecystectomy by the help of the modified D-xylose-absorption test. A characteristic dependence upon the age for the process of intestinal absorption was demonstrated in the elderly not only preoperatively but also postoperatively. The effective intestinal absorption of D-xylose normalized postoperative by in freshly operated older patients more slowly than in younger ones.

Aged↗
PubMed1978

Effects of vasoactive intestinal polypeptide on intestinal absorption and blood flow.

1. Intestinal absorption and blood flow in anaesthetized dogs was determined after I.V. infusion of vasoactive intestinal polypeptide (VIP) (1.75-175 ng/min) to determine the contribution of the cardiovascular changes to transport. 2. 22Na and 3H2O were utilized to determine the unidirectional fluxes of Na and H2O from saline perfused through the ileal lumen and the clearances of 3H2O were used to determine total and absorptive site blood flow. 3. Net Na and H2O absorption were reversed to secretion by VIP at 175 ng/min due to a significant decrease in unidirectional absorptive fluxes and smaller increases in secretory fluxes. 4. Arterial pressure and absorptive site blood flow were reduced in proportion to the changes in Na and H2O fluxes. 5. Total and absorptive site blood flow decreased and the blood flow resistances increased. 6. Prior treatment with guanethidine to suppress sympathetic effects did not greatly affect the responses to VIP. Prior treatment with atropine to suppress cholinergic effects inhibited most of the effects of VIP. 7. Absorptive site blood flow was linearly related to absorptive fluxes of Na and H2O but with different slopes for results from atropinized dogs as compared to those from dogs given VIP alone or VIP plus guanethidine. 8. It was concluded that VIP reduces gut absorption through a generalized cardiovascular effect and also through a mechanism which depends on the release of ACh by the gut.

Animals↗
PubMed1978

Intestinal absorption of fluoride preparations.

Gastric intestinal absorption of five different preparations of sodium fluoride was measured by means of ten hour urinary excretion. Best absorption was by nonenteric coated sodium fluoride. All three enteric coated preparations showed poorer absorption, with marked individual variations. Florical, the currently available preparation, showed better absorption than any enteric coated tablets and only slightly less than sodium fluoride alone. For active cochlear otospongiosis two capsules three times a day should be prescribed.

Administration, Oral↗
PubMed1976

Intestinal absorption of phosphate: action of protein synthesis inhibitors and glucocorticoids in the rat.

The effect of actinomycin D, cycloheximide and glucocorticoids on the intestinal absorption of phosphate was studied. The effective intestinal absorption of 32P and 47Ca was determined simultaneously in intact rats in vivo using a whole body counter. Both, actinomycin D and cycloheximide caused a significant diminution of the intestinal absorption of phosphate whereas calcium absorption was not altered. Experiments with the in situ ligated loop technique were performed to eliminate the possibility that the action of the protein synthesis inhibitors could be due to an altered intestinal motility effect. Phosphate absorption was also significantly diminished under this condition. On the other hand, the administration of glucocorticoids produced a significant inhibition of phosphate and calcium absorption in the rat in vivo. The reported results indicate that proteins and/or enzymes with a rapid turn-over are involved in the mechanism of phosphate intestinal absorption, and confirm previous observations that phosphate and calcium are transported across the intestine by different mechanisms.

Animals↗
PubMed1976

Intestinal absorption of L-tryptophan in scleroderma.

The purpose of this investigation was to study the intestinal absorption of L-tryptophan and to assess the absorptive function of the intestine in scleroderma. The oral L-tryptophan loading test was performed in 31 cases of systemic scleroderma (progressive systemic sclerosis, PSS) and 3 cases of localized scleroderma. Serum levels of tryptophan and urinary excretion of indole-acetic acid (IAA) and indican (IS) were determined in order to assess intestinal absorption of tryptophan. In 10 cases the D-xylose test and in 4 cases Schilling's test was also performed. Furthermore, in vitro binding of L-tryptophan by plasma proteins in PSS and in other skin diseases as controls was studied. The normal increase in serum tryptophan after loading was noted in 17 cases (in 14 cases of PSS with a mild, slow progression in 3 cases of PSS with a severe, rapidly progressing course). In 10 of these cases, urinary excretion of IAA was higher than normal and in normal and in 3 cases excretion of urinary IS was also above normal. On the other hand, in 14 cases of severe, rapidly progressing PSS and in 2 of 3 cases of widespread linear scleroderma, serum levels of tryptophan were markedly depressed after loading, while urinary excretion of IAA and IS was normal. In all 4 cases studied, Schilling's test was normal, and only in 2 of 10 cases of PSS was the D-xylose test abnormal. It is concluded that in the majority of cases of PSS, intestinal absorpiton of tryptophan is normal as also is the absorptive function of the intestine. The slight rise in serum tryptophan after loading in some cases of PSS may be a result of increased binding of tryptophan by albumin.

Adolescent↗
PubMed1992

Improvement of large intestinal absorption of insulin by chemical modification with palmitic acid in rats.

The intestinal absorption of 125I-labelled palmitoyl insulin was examined following administration into in-situ closed large intestinal loops of rats. When mono- and dipalmitoyl insulins (Palins-1 and Palins-2, respectively) were administered in polyoxyethylene hydrogenated castor oil (HCO 60) micellar system into intestinal loops, a marked increase in plasma radioactivity and a corresponding disappearance of residual radioactivity in the intestinal lumen were observed in the following rank order: Palins-2 greater than Palins-1 greater than native insulin. In addition, the derivatives were more stable than native insulin in the mucosal tissue homogenates of the large intestine. These results suggest that chemical modification of insulin with palmitic acid may not only increase the lipophilicity of insulin but also reduce its degradation, resulting in the increased transfer of insulin across the large intestinal mucous membrane. The linoleic acid-HCO 60 mixed micelles system did not have a significant effect on the large intestinal absorption of radioactivity associated with the lipophilic insulin analogues.

Animals↗
PubMed1978

Effect of low calcium and low phosphorus diets on the intestinal absorption of phosphate in intact and parathyroidectomized pigs.

The intestinal absorption of phosphate has been studied in conscious pigs, each prepared with a Thiry-Vella loop of jejunum. The feeding of diets low in either calcium or phosphorus caused a significant increase in the efficiency of absorption of phosphate from the solution used to perfuse the jejunal loop in both intact and parathyroidectomized (PTX) pigs. An intravenous infusion of parathyroid hormone (0.22 u. kg-1 h-1) into a PTX pig also enhanced the absorption of phosphate. The increase in the absorption of phosphate when the low phosphorus diet was fed was not caused by an increase in the concentration gradient of phosphate ions between the jejunal lumen and blood. It is concluded that the intestinal absorption of phosphate shows similar changes to those of calcium when diets low in calcium or phosphorus are fed and that parathyroid hormone, although capable of stimulating the absorption of phosphate, is not essential for this adaptation. These effects are probably brought about by changes in the renal production and mucosal uptake of 1,25-dihydroxycholecalciferol, the active metabolite of vitamin D3.

Animals↗
PubMed1992

Improvement of intestinal absorption of thyrotropin-releasing hormone by chemical modification with lauric acid.

Intestinal absorption of 125I-labelled lauryl thyrotropin-releasing hormone (Lau-TRH), a novel lipophilic derivative of TRH, was examined by rat in-situ closed intestinal loops. At a dose of 1 mumol per rat into the small intestine, a significant increase in percent of dose in plasma radioactivity of Lau-TRH was observed in comparison with that of TRH. A dose-dependent decrease in percent of dose in plasma radioactivity of TRH was noted, suggesting a saturable process of TRH transport. In contrast, the percent of dose in plasma radioactivity of Lau-TRH increased with increasing dose of Lau-TRH. The stability of TRH and Lau-TRH was studied in plasma and rat small intestinal homogenates. Lau-TRH was more stable than TRH in rat plasma. These results suggest that chemical modification of TRH with lauric acid may not only increase the lipophilicity of TRH but also reduce the degradation of TRH, resulting in the increased plasma radioactivity of TRH. On the other hand, Lau-TRH was gradually converted to TRH in the intestinal mucosal homogenate. These findings indicate that chemical modification of TRH with lauric acid might be a useful approach for improving the intestinal absorption of this peptide.

Animals↗