Characterisation of penicillin-G uptake in rabbit small-intestinal brush-border membrane vesicles.
Uptake of penicillin-G has been studied in rabbit intestinal brush-border membrane vesicles (BBMV). Penicillin-G was transported into the lumen of BBMV via an H+-dependent, Na+-independent uptake system. This was a saturable carrier-mediated process, which adhered to Michaelis-Menten kinetics, having a pH optimum of 4.5 and resulting in a net-negative charge transfer. Vmax was 59 nmol penicillin-G (mg protein)-1 (30s)-1 and Km 22.7 mM. Ampicillin, penicillin-V, cefadroxil, cephalexin, cephalothin, cephradine, L-carnosine, glycyl-L-alanine, glycyl-L-tyrosine and glycylglycylglycine inhibited the uptake of penicillin-G. However, glycylsarcosine stimulated uptake by 92%. Countertransport experiments suggested that this effect took place at the active site of the transporter. Penicillin-G uptake appeared to be mediated via a common transport system shared by penicillins, cephalosporins and peptides.
Poschet
J F
JF
Department of Gastroenterology, Medical School of St. Bartholomew's Hospital, University of London, London, UK.
Hammond
S M
SM
Fairclough
P D
PD
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D004563:Electrochemistry; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007421:Intestine, Small / Q000378:metabolism* / Q000648:ultrastructure; D007700:Kinetics; D007769:Lactams / Q000494:pharmacology; D008297:Male; D008564:Membrane Potentials; D008871:Microvilli / Q000378:metabolism*; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000494:pharmacology; D010400:Penicillin G / Q000493:pharmacokinetics*; D010406:Penicillins / Q000493:pharmacokinetics*; D011817:Rabbits
D000596:Amino Acids; D007769:Lactams; D009842:Oligopeptides; D010406:Penicillins; D010400:Penicillin G