This article describes a surgical procedure for cannulating the carotid artery in an anesthetized rat model. The method involves precise dissection and ligation techniques to ensure proper placement of the cannula for subsequent experiments.
Prepare an anesthetized rat in a supine position.
Incise longitudinally through the skin above the anatomical left aspect of the trachea.
Dissect the subcutaneous connective tissue. Retract the neck muscles, revealing the left carotid artery.
Isolate an artery section and place silk sutures around both ends.
Ligate the suture placed distal from the heart to prevent blood flow toward the head region.
Obstruct blood flow through the artery section. Make an incision on the top surface of the artery.
Insert an anticoagulant-filled cannula connected to an anticoagulant-filled syringe into the incised section.
Advancing the cannula to the predetermined depth, inject the anticoagulant solution into the cannula.
Draw back a small blood volume through the cannula to confirm unobstructed flow.
Flush with the anticoagulant solution and seal the cannula's end to prevent blood leakage.
Secure the cannula within the artery. Close the surgical incision.
The cannulated rat model is ready for experiments.
To cannulate the carotid artery, first, mark the carotid artery cannula 2.5 centimeters from the beveled tip to identify the portion of the tubing to insert into the artery. Then, connect the unbeveled end of the cannula to a 25-gauge needle, attached to a syringe filled with anticoagulant solution, and fill the cannula with the solution, making sure no air gaps are present.
Next, make a 1 to 1.5-centimeter longitudinal incision through the skin layer above the left of the trachea in the sagittal plane, and then use blunt tip forceps to dissect the subcutaneous connective tissue, and expose the underlying paired neck muscles.
Retract the neck muscles to reveal the pulsating left carotid artery located approximately 1 centimeter below the skin surface. Then, clean the overlying connective tissue from the artery by blunt dissection, and use blunt tissue forceps to isolate an approximate 1-centimeter section of the artery.
Next, use fine-tipped forceps to thread two silk sutures underneath the carotid artery, placing them at each end of the isolated artery section. Then, tie off the suture furthest from the rat's heart and clavicle, and place a pair of straight fine-tipped forceps under the carotid to occlude the blood flow through the artery.
Now, using fine-tipped iris scissors, make a small incision on the top surface of the artery, about one-third of the way down from the top of the isolated area. Insert the tip of the cannula into the artery with a pair of curved-tip forceps.
Once inserted, remove the straight fine-tipped forceps occluding the blood flow and advance the cannula 2.5 centimeters 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. Then, use a small artery clamp to hold the cannula inside the artery.
Inject anticoagulant solution into the cannula, followed by drawing back a small amount of blood to confirm the patency of the tubing. Then, flush the cannula with anticoagulant solution and seal the end using the flame of a lighter.
Finally, use the sutures to tie the cannula in place, and remove the artery clamp. Then, secure a third suture around the artery and cannula; shorten the length of the sutures around the artery and close the neck wound with more sutures.
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