CHARACTERISTICS OF UPTAKE OF CEFROXADINE BY RABBIT SMALL-INTESTINAL BRUSH-BORDER MEMBRANE-VESICLES

Citation
S. Kitagawa et Y. Sugaya, CHARACTERISTICS OF UPTAKE OF CEFROXADINE BY RABBIT SMALL-INTESTINAL BRUSH-BORDER MEMBRANE-VESICLES, Biological & pharmaceutical bulletin, 19(2), 1996, pp. 268-273
Citations number
34
Categorie Soggetti
Pharmacology & Pharmacy
ISSN journal
09186158
Volume
19
Issue
2
Year of publication
1996
Pages
268 - 273
Database
ISI
SICI code
0918-6158(1996)19:2<268:COUOCB>2.0.ZU;2-D
Abstract
Characteristics of transport of an oral animocephalsoporin. cefroxadin e. in rabbit small intestinal brush border membrane vesicles were exam ined. Uptake rate of cefroxadine was saturable in the presence of an i nward H+ gradient, and kinetic parameters were similar to those of cep hradine. However, the uptake rate was almost linear with the concentra tion in the absence of inward H+ gradient up to 5 mM. Overshoot phenom enon was observed in the presence of an inward H+ gradient at 37 degre es C, but it disappeared with decrease of temperature. The Arrhenius p lot of uptake rate constant showed a break point at approximately 30 d egrees C. Cefroxadine uptake was optimum in the vicinity of pH 5.5 at 37 degrees C, but the dependence on extravesicular pH disappeared at 1 5 degrees C. The uptake of cefroxadine but the inhibition was only sli ght in the absence of an inward H+ gradient. Alkyl alcohols such as n- hexyl alcohol also inhibited H+-coupled uptake of cefroxadine at the c oncentration range at which the alcohols increased the membrane fluidi ty, and overshoot phenomenon diminished, suggesting that H+-coupled tr ansport of cefroxadine is sensitive to the alcohol-induced increase in membrane fluidity. On the other hand, the alcohols rather stimulated its uptake in the absence of an H+ gradient.