0000000000425065
AUTHOR
M J Moll-navarro
Influence of gamma-aminobutyric acid on baclofen intestinal absorption.
Since previous studies suggested that baclofen absorption in the rat middle intestine was inhibited by beta-alanine and therefore mediated, at least in part, by the beta-aminoacid carrier, we focused our new studies on the analysis of the possible inhibition of the drug by a gamma-aminoacid model compound, gamma-aminobutyric acid (GABA). A rat jejunum in situ study was undertaken in order to evaluate the effect of GABA on baclofen absorption and to establish the inhibition model. Assays using isotonic perfusion solutions of 0.5 mM baclofen with starting GABA concentrations ranging from 0 to 100 mM are reported. The results show that the absorption rate pseudoconstants of the drug decrease a…
Intestinal absorption pathway of gamma-aminobutyric acid in rat small intestine.
Intestinal absorption of gamma-aminobutyric acid (GABA), as a model compound for gamma-aminoacids, has not been extensively studied from the kinetic viewpoint. Since data from our laboratory suggested that some competition arises between intestinal absorption of beta-alanine and GABA and since our intent was to maintain the aqueous stagnant diffusion layer in order to approach absorption tests to in vivo physiological conditions, a rat jejunum in situ study was undertaken in order to gain an insight into the mechanism of GABA absorption. In the present paper, results from assays using isotonic perfusion solutions with starting GABA concentrations ranging from 1 to 50 mM are reported. They s…
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 …