Preincubation accelerates taurocholate uptake into isolated liver cells

Initial rates of taurocholate uptake into isolated hepatocytes stored at 0°C increased 3-fold during a 25 min preincubation. Concomitantly, $\text{V}$ increased while $\text{K}{}_{\mathrm{<mtext>m</mtext>}}$ remained unaffected. There are several possible explanations for the preincubation effects, such as new synthesis of carrier protein, altered fluidity of the membrane or stimulation of the sodium-dependent taurocholate uptake via a change in the cation distribution. The experiments presented strongly favor the latter explanation as the sodium gradient as well as the uptake of the bile acid reach their steady state within 20–30 min and replacement of sodium by potassium in the medium abolished the effect.