0000000000353807
AUTHOR
A. Polache
Effects of chronic alcohol consumption on enzyme activities and active methionine absorption in the small intestine of pregnant rats.
The present study evaluates the effect of chronic alcohol intake on the intestinal transport of methionine during pregnancy. For this purpose, we have used an in vitro technique that allows measurement of the unidirectional influx of the amino acids across the brush-border membrane of the rat mid-jejunum, and the basolateral membrane enzyme Na+, K+-ATPase was also evaluated in the duodenum and jejunum. For chronic alcohol treatment, the rats were fed a liquid diet containing ethanol (36% of calories) or an isocaloric diet-(pair-fed control) for 5 weeks before and during pregnancy. Animals were killed at 21 days of gestation. Results from the kinetic analysis revealed that chronic ethanol tr…
Evidence of competitive inhibition for the intestinal absorption of baclofen by phenylalanine
Abstract Previous studies showed that the absorption of the antispastic drug baclofen, in the rat middle intestine, is inhibited by β-alanine, γ-aminobutyric acid (GABA) and leucine. It was concluded that baclofen intestinal transport was mediated, at least in part, by the β-, γ- and α-amino acid carriers. We therefore focused our next studies on the analysis of the possible inhibition of drug absorption by an aromatic α-amino acid model compound, phenylalanine. An in situ study in the rat small intestine was undertaken in order to evaluate the effect of phenylalanine on baclofen absorption and to establish the inhibition model. Assays using isotonic perfusion solutions of 0.5 mM baclofen w…
Influence of Chronic Alcohol Intake on Intestinal Taurine and Antipyrine Transport in Pregnant Rats
Taurine is a nonessential amino acid that plays a critical role in development. However, biosynthetic capacity is almost negligible in the fetus and must be supplied by the mother. Therefore, when maternal taurine status is depressed during gestation, fetal tissue taurine concentrations can also be compromised. In the present study, the effect of chronic alcohol intake on the intestinal transport of taurine during pregnancy has been investigated by an in vitro technique that allows measurement of the unidirectional influx of the amino acid across the intact rat mid jejunum. The influence of alcohol intake on the passive component of the intestinal transport was also investigated with antipy…
Effects of Ethanol on Intestinal Absorption of Drugs
The effect of chronic alcohol intake on the intestinal absorption of seven compounds belonging to a homologous series (ciprofloxacin derivatives) was evaluated using an in situ rat gut technique that measures the intrinsic absorption rates of the compounds both in control and chronic alcohol-fed rats. For chronic alcohol treatment, the animals were fed a liquid diet containing ethanol (36% of calories), whereas an isocaloric diet was given to the pair-fed control animals. The biophysical absorption model, relating the intestinal absorption rate constants and partition indexes of the tested compounds, was then established either for control or alcohol-fed animals. Differences were analyzed a…
Evidence of competitive inhibition of methotrexate absorption by leucovorin calcium in rat small intestine
Abstract The effect of leucovorin calcium on the intestinal absorption of methotrexate in rat small intestine was investigated using an in situ rat gut technique. First, the kinetic absorption in situ parameters for methotrexate in solution were obtained: V m =21.54 (±2.22) μ M/h; K m =10.51 (±1.08) μ M; k a =0.26 (±0.03) h −1 and AIC=−188.63. The inhibitory effect of leucovorin calcium in methotrexate intestinal absorption has been investigated by perfusing of 10 μ M methotrexate isotonic solutions containing increasing concentrations of leucovorin calcium (10–500 μ M), and the remaining concentrations of both compounds were measured. A competitive inhibition of methotrexate absorption was…
Interaction of Taurine on Baclofen Intestinal Absorption: A Nonlinear Mathematical Treatment using Differential Equations to Describe Kinetic Inhibition Models
Previous studies showed that the in situ absorption of baclofen in rat jejunum was inhibited by beta-alanine, a nonessential amino acid, and therefore mediated, at least in part, by some beta-amino acid carrier. In this paper a similar study was undertaken using taurine, a sulfonic beta-amino acid, in order to evaluate its effect and to establish a general inhibition model. To achieve this goal, remaining concentrations of inhibitor were also measured and incorporated into the model. Previously, kinetic absorption in situ parameters for taurine in free solution were obtained: Vm = 27.73 +/- 9.99 mM h-1, K(m) = 8.06 +/- 2.82 mM, Ka (passive difussion component) = 0.40 +/- 0.28 h-1. Isotonic …