Naasani I, Sato K, Iseki K, Sugawara M, Kobayashi M, Miyazaki K
Department of Pharmacy, Hokkaido University Hospital, School of Medicine, Hokkaido University, Sapporo, Japan.
Biochim Biophys Acta. 1995 Sep 12;1231(2):163-8. doi: 10.1016/0005-2728(95)00073-r.
The transport characteristics of ceftibuten, a dianionic cephem antibiotic, in rat renal and intestinal brush-border membranes were compared. Ceftibuten transport was mediated by two transport systems in the renal brush-border membrane and by one transport system in the intestinal brush-border membrane. The apparent kinetic parameters for the uptake of ceftibuten by the renal brush-border membrane vesicles, respectively, were: Km1, Km2 values of 26 and 1946 microM and Vmax1, Vmax2 values of 105 and 1400 pmol/mg protein per 30 s. The apparent kinetic parameters for the uptake by the intestinal brush-border membrane vesicles were: Km of 425 microM and Vmax of 1701 pmol/mg protein per 30 s. In the renal brush-border membrane, L-Ala-L-Pro was partially competitive and competitive inhibitor for the uptake by the high and low affinity systems, respectively. However, L-Ala-L-Pro was a non-competitive inhibitor for the uptake by the intestinal brush-border membrane vesicles. L-Carnosine was a specific and competitive inhibitor for the high affinity system in the renal brush-border membrane, while it had no effect on the low affinity system of the kidney or on the transport system of the intestine. It was concluded that the transport characteristics of ceftibuten in the renal and intestinal brush-border membranes are similar in some aspects but they are not identical.
比较了二阴离子头孢烯抗生素头孢布烯在大鼠肾和肠刷状缘膜中的转运特性。头孢布烯的转运由肾刷状缘膜中的两个转运系统和肠刷状缘膜中的一个转运系统介导。肾刷状缘膜囊泡摄取头孢布烯的表观动力学参数分别为：Km1、Km2值为26和1946μM，Vmax1、Vmax2值为每30秒105和1400 pmol/mg蛋白质。肠刷状缘膜囊泡摄取的表观动力学参数为：Km为425μM，Vmax为每30秒1701 pmol/mg蛋白质。在肾刷状缘膜中，L-丙氨酰-L-脯氨酸分别是高亲和力和低亲和力系统摄取的部分竞争性抑制剂和竞争性抑制剂。然而，L-丙氨酰-L-脯氨酸是肠刷状缘膜囊泡摄取的非竞争性抑制剂。L-肌肽是肾刷状缘膜中高亲和力系统的特异性竞争性抑制剂，而对肾的低亲和力系统或肠的转运系统没有影响。得出的结论是，头孢布烯在肾和肠刷状缘膜中的转运特性在某些方面相似，但并不相同。
