豚鼠离体回肠细胞对牛磺胆酸盐的摄取动力学

Kinetics of taurocholate uptake by isolated ileal cells of guinea pig.

作者信息

Schwenk M, Hegazy E, Lopez Del Pino V

出版信息

Eur J Biochem. 1983 Mar 15;131(2):387-91. doi: 10.1111/j.1432-1033.1983.tb07275.x.

DOI:10.1111/j.1432-1033.1983.tb07275.x

Abstract

Carrier-mediated uptake of taurocholate by ileal cells of guinea pig had an activation energy of 66 kJ/mol. There was no distinct pH optimum in the physiological pH range. Uptake was efficiently inhibited by cholate and taurochenodeoxycholate in a competitive manner, but less inhibited by bromosulfophthalein and not inhibited by taurine. The rate of uptake was related to the extracellular Na+ concentration up to 90 mM Na+. Stimulation by Na+ (up to sevenfold) occurred only in the presence of a transmembrane Na+ gradient, whereas high extracellular (Na+) in the absence of gradient did not stimulate. It is suggested that taurocholate is bound to a steroid-binding site of the carrier. The energy for the intracellular accumulation is largely provided by cotransport with Na+.

摘要

豚鼠回肠细胞通过载体介导摄取牛磺胆酸盐的活化能为66 kJ/mol。在生理pH范围内没有明显的最适pH值。摄取被胆酸盐和牛磺鹅去氧胆酸盐以竞争性方式有效抑制，但被溴磺酞抑制程度较小，且不被牛磺酸抑制。摄取速率与细胞外Na⁺浓度相关，直至90 mM Na⁺。只有在存在跨膜Na⁺梯度时，Na⁺（高达七倍）才会产生刺激作用，而在没有梯度的情况下，高细胞外（Na⁺）不会产生刺激作用。提示牛磺胆酸盐与载体的类固醇结合位点结合。细胞内积累的能量主要由与Na⁺的协同转运提供。