Effects of Glyco- and Tauro-Cholic and Chenodeoxycholic Acids on Lymphatic Absorption of Micellar Cholesterol and Sitosterol in Rats

Lymphatic absorption of [³H]cholesterol and [¹⁴C]sitosterol from a mixed micellar solution containing sodium taurocholate or taurochenodeoxycholate, and glycocholate or glycochenodeoxycholate infused into the duodenum was compared in rats with lymph and bile drained. Absorption of [³H]cholesterol into the thoracic duct lymph was clearly higher than that of [¹⁴C]sitosterol irrespective of the source of bile salts. Lymphatic absorption of cholesterol for 24 h was reduced by 23% in the taurochenodeoxycholate micelles compared with the taurocholate micelles, and the reduction of sitosterol was 61%. A similar extent of reduction was also observed between the glycocholate and glycochenodeoxycholate micelles. The absorption rate of cholesterol in relation to sitosterol (cholesterol/sitosterol ratio) was significantly higher in the chenodeoxycholate micelles (around 12) than the cholate micelles (around 6 to 7). Thus, the difference in the absorption rate between cholesterol and sitosterol could not be explained by the differential affinity of these sterols for the different bile salt micelles, and was largely influenced by the source of bile acids.