Kinetics of Taurocholate Uptake by Isolated Ileal Cells of Guinea Pig

Publisher Website
Google Scholar
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+.