Intestine Absorption (Franz Cell, Porcine Intestine, Krebs-Ringer)

Materials Needed:

• Franz diffusion cells
• Porcine intestine (fresh or properly stored)
• Krebs-Ringer buffer (either HEPES or sodium bicarbonate-buffered, depending on setup)
• Donor and receptor compartments for Franz cells
• Magnetic stirrers
• Syringes and needles
• pH meter
• Incubator or water bath (if needed for maintaining temperature)
• Analytical instruments (e.g., HPLC, spectrophotometer) for sample analysis
• Absorption compound (test substance)

Preparation:

1. Prepare Krebs-Ringer Buffer:

   • For HEPES-buffered: Dissolve the appropriate amounts of NaCl, KCl, CaCl₂, MgSO₄, NaH₂PO₄, glucose, and HEPES in distilled water. Adjust pH to 7.4.
   • For sodium bicarbonate-buffered: Prepare similarly but use NaHCO₃ instead of HEPES, and adjust pH with a CO₂ environment if necessary.

2. Prepare Porcine Intestine:

   • Obtain fresh porcine intestines from a suitable source.
   • Clean the intestine to remove any contents and mucosal debris.
   • Cut the intestine into appropriate sections for mounting on the Franz cell.

3. Mount the Intestinal Tissue:

   • Carefully mount a section of the intestine between the donor and receptor compartments of the Franz cell. Ensure no leaks and that the tissue is securely in place.

Experiment Setup:

4. Fill Receptor Compartment:

   • Fill the receptor compartment with the Krebs-Ringer buffer, ensuring that it is well-mixed and aerated. This compartment will mimic the blood side of the intestine.
   • Place a magnetic stir bar in the receptor compartment for continuous mixing.

5. Add Test Compound to Donor Compartment:

   • Apply the test compound (the substance you want to study for absorption) to the donor compartment. This compartment represents the lumen side of the intestine.
   • The compound should be in a suitable solvent or vehicle that does not damage the tissue.

6. Maintain Experimental Conditions:

   • Place the Franz cells in an incubator or water bath to maintain physiological temperature (usually around 37°C).
   • Ensure continuous stirring of the receptor compartment to simulate blood flow and to prevent boundary layer formation.

Sampling:

7. Sample Collection:

   • At predetermined time intervals (e.g., every 30 minutes or hourly), withdraw small aliquots from the receptor compartment using a syringe.
   • Replace the withdrawn volume with fresh Krebs-Ringer buffer to maintain constant volume.

8. Analyze Samples:

   • Analyze the collected samples using appropriate analytical techniques (e.g., HPLC, UV-spectrophotometry) to determine the concentration of the test compound.
   • Plot the concentration of the test compound in the receptor compartment over time to assess the absorption rate.