Study on the absorption site of divalent cations in the intestinal loop, using the multitracer technique

The rats were fasted overnight and then anesthetized with pentobarbiturate. Segments of the duodenum, jejunum, ileum, and colon of 6 cm length were isolated. Each specimen was everted to prepare a sac with mucosa on the outside. Each gut sac was filled with 600μl of multitracer solution and then immersed in 10ml of the buffer solution and incubated with bubbling 95% O2 and 5% CO2 at 37 ◦C for 90 minutes. After incubation, 300μl of the solution from the serosal side, and 3ml from the mucosal side were removed. The activity of each tracer in the sample was determined by gammaray spectrometry using high-purity Ge detectors. Data were expressed as an S/M ratio (the serosal side content is indicated as S and the mucosal side content as M). An S/M ratio greater than 1.0 can be considered as a mechanism of active transport of the minerals from the mucosal into the serosal side.