After anesthetizing the mouse, place it in a supine position on a heated surgical surface. Apply eye ointment and perform toe pad pinches to ensure the animal is adequately anesthetized. Lift the skin of the abdomen.
With a pair of scissors, make a longitudinal incision at the midline from the umbilicus to the xiphoid process and caudally towards the abdomen's base. Make a similar incision into the peritoneum without perforating or damaging the intestines, diaphragm, or liver. Next, make a full length transverse incision on both sides of the umbilicus to expand the surgical field.
Then use clean gauze soaked in warm PBS to move the large and small intestines to the right and expose the IVC below. With a cotton swab, gently manipulate the intestinal segments within the surgical field to locate the portal vein at the root of the mesentery. Then use a dissecting microscope to carefully pass a 7-0 prolene suture behind the portal vein near the hepatic hilum.
Next, insert a 28 gauge half inch needle of a heparinized one cubic centimeter insulin syringe into the IVC. Collect 0.2 to 0.3 milliliters of the blood sample. Leave the needle inside the IVC to avoid the bleeding that would occur with removal.
Now, gently tie the 7-0 prolene ligature around the portal vein. Insert the 28 gauge half inch needle of another heparinized insulin syringe into the portal vein. Aspirate to slowly collect up to 0.5 milliliters of blood from the portal vein.
Once blood collection is complete, remove the needles from the IVC and the portal vein. Transfer the blood samples from syringes to 1.5 milliliter heparinized tubes. Place the tubes on ice for future processing.
