Cannulation of the Carotid Artery in a Rat Model

All procedures involving animal models have been reviewed by the local institutional animal care committee and the JoVE veterinary review board.

1. Cannulation of the Carotid Artery

The carotid artery cannulation may be performed before or after the cannulation of the mesenteric lymph duct. Some operators prefer to cannulate the carotid artery prior to cannulating the lymph duct so as to reduce potentially dislodging the lymph cannula when moving the animal.

1. Place a mark on the carotid artery cannula 2.5 cm from the bevel tip to identify the portion of the tubing to insert into the artery. Connect the other end of the cannula (i.e., without bevel) to a 23 or 25-G needle attached to a syringe filled with anticoagulant solution and fill the cannula with the anti-coagulant solution making sure no air gaps are present.
2. To facilitate cannulation, place the anesthetized rat in dorsal recumbency with the neck stretched and the head pointing toward the operator. Note that some operators prefer to perform this technique with the rat's tail pointing toward the operator.
3. Place a 1 – 1.5 cm longitudinal incision through the skin layer above the left of the trachea in the sagittal plane.
4. Dissect the subcutaneous connective tissue using blunt tip forceps to expose the underlying paired neck muscles.
5. Retract the neck muscles to reveal the left carotid artery (located ~1 cm below the skin surface and pulsing). Clean the overlying connective tissue from the artery by blunt dissection.
6. Isolate a ~1 cm section of the artery carefully using blunt tissue forceps, taking care not to damage the adjacent vagal nerve tract. Perform this by opening and closing the blunt tip forceps vertically along either side of the artery to free it from the surrounding tissue and vagus nerve.
7. Using fine-tip forceps, thread two silk sutures underneath the carotid artery and place them at each end of the isolated artery section. Tie off the suture closest to the operator and furthest from the rat's heart and clavicle (Figure 1A).
8. Occlude blood flow through the artery by placing a pair of straight fine-tip forceps underneath the artery (Figure 1B).
9. Using the fine-tip iris scissors, place a small incision on the top surface of the artery (about 1/3 of the way down from the top of the isolated area). Flush any spilled blood on the surface of the artery with heparinized saline and gently wipe using cotton tips.
10. Insert the tip of the cannula into the artery with a pair of curved tip forceps. Once inserted, remove the straight fine tip forceps occluding the blood flow and advance the cannula 2.5 cm into the artery using two pairs of forceps, one to hold the cannula inside the artery to stop blood from leaking back and the other to insert the cannula.
11. Use a small artery clamp to hold the cannula inside the artery and remove the straight fine tip forceps that were placed below the artery in step 1.8 to occlude the blood flow.
12. Confirm the patency of the cannula by injecting an anti-coagulant solution into the cannula and drawing back a small amount of blood (Figure 1C). Then flush the cannula with an anticoagulant solution and seal the end using the flame of a lighter or a cannula plug.
13. Tie the cannula in place with the two sutures placed under the artery in step 1.8.
14. Remove the artery clamp and secure a third suture around the artery and cannula. Close the neck wound with sutures.