Distribution of PABA and 14C-labelled PABA in rat organism and its changes during post-irradiation disease.
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Aminobenzoates↗
Biomedical subjects
Z Fendrich
Publications and source records attributed to Z Fendrich.
Acetylation of PABA in perfused isolated rat liver in the course of acute radiation sickness.
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Acetates↗
Pharmacokinetic examination of antipyrine passage through the placenta and the small intestine in rats.
The placental and small intestinal barriers, though obviously different, show many functional as well as morphological similarities. When the surface area of both barriers in man was recalculated to a unit of body weight, nearly identical values (2.71 and 2.86 m2/kg of body mass, respectively) were obtained. The aims of the present study were (1) to compare mutual permeability of these two barriers to antipyrine (AP), and (2) to describe pharmacokinetics of AP in pregnant and non-pregnant rats. In placental studies AP showed that its rapid transfer through the placenta (k(tr) = 0.046 min(-1)) was governed by the mechanism of passive diffusion. In the closed circuit, FMCR(eq) was 1.085, t(eq) was 112.10 min and k(eq) was 0.020 min(-1). Absorptive studies performed on the rat small intestine indicated an identical mechanism of drug transport. The apparent first-order absorption rate constant of AP was 0.479 min(-1), and Tmax was 8.95 minutes. Differences in AP pharmacokinetics between pregnant and non-pregnant rats were significant during the distribution phase (t(1/2) = 3.78 and 5.87 min, respectively), whereas the elimination phase was unaffected. AP has been demonstrated, as expected, to be an excellent marker for drug transport studies through different body barriers.
Animals↗
Corticosterone transfer and metabolism in the dually perfused rat placenta: effect of 11beta-hydroxysteroid dehydrogenase type 2.
Although rat is the most widely used model of glucocorticoid programming of the fetus, the role of rat placental 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2) in the transplacental pharmacokinetics of the naturally occurring glucocorticoid, corticosterone, has not yet been fully elucidated. In this study, expression of 11beta-HSD2 in the rat placenta on two different gestation days (16 and 22) was examined using quantitative RT-PCR and Western blotting, and dually perfused rat term placenta was employed to evaluate its functional capacity to transfer and metabolize corticosterone. Marked decrease in placental expression of 11beta-HSD2 toward term was observed on both mRNA and protein levels. In perfusion studies, increasing maternal corticosterone concentration from 3 to 200 nM resulted in the fall of 11beta-HSD2 conversion capacity from 64.3 to 16.3%, respectively. Enzyme saturation occurred at about 50 nM substrate concentration. When delivering corticosterone (3 or 100 nM) from the fetal side, a similar decline of 11beta-HSD2 conversion capacity was observed (66.5% and 48.5%, respectively). Addition of carbenoxolone (10 or 100 microM), a non-specific 11beta-HSD inhibitor, to maternal perfusate decreased conversion capacity from 66.7 to 12.6 or 8.1%, respectively. Similarly potent inhibitory effect was observed in feto-maternal studies. Neither saturation nor inhibition of 11beta-HSD2 was associated with transformation of corticosterone in metabolites other than 11-dehydrocorticosterone. These data suggest that 11beta-HSD2 is the principal enzyme controlling transplacental passage of corticosterone in rats and is able to eliminate corticosterone in both maternal and fetal circulations.
11-beta-Hydroxysteroid Dehydrogenase Type 2↗