To begin, assemble two sets of 350-milliliter tubes with different concentrations of sodium chloride. Dip the prepared intestinal sacs in the specified tubes for 30 minutes and 60 minutes for each set. After the designated time, empty the solution inside the sac in a separate 1.5-milliliter microcentrifuge tube and determine the volume.
Using a two-milliliter syringe, aspirate the liquid inside the sac. To create a standard curve for histidine, prepare solutions of varying histidine concentrations using histidine stock solutions and water. Then, add sulfanilic acid and sodium nitrate to each tube.
After incubating the tubes for five minutes at room temperature, add one milliliter of sodium carbonate and ethanol to each tube. Finally, measure the absorbance at 490-nanometer wavelength. Histidine estimation using Pauly's reaction followed Lambert-Beer's law til 300 micromolars of histidine.
A correlation was observed between the uptake of histidine and sodium concentrations in jejunal enterocytes.
