Rat Blood Collection Protocols

Rat should be fully anesthetized (e.g., unresponsive to toe pinch).

Open Chest Method

1. Have ready a syringe (3–10 ml) containing ~0.3 ml air and with a 20 gauge needle attached.
2. Make an incision at the level of the xiphoid process and hold the xiphoid with a hemostat or forceps.
3. Beginning at the xiphoid, cut along the full length of the sternum just to the rat’s right of the midline, then make a lateral incision through the chest wall laterally to the rat’s left, just cranial to the diaphragm. Do this quickly, as there will be arterial bleeding from the chest wall incisions.
4. Continuing to hold the xiphoid, retract the chest wall flap laterally, and expose the heart with blunt dissection of the pleura and pericardium. If necessary, make a lateral incision to the right in the chest wall (there should be adequate exposure of the heart without the second lateral incision if the initial midline incision is slightly to the right of the sternum).
5. Insert the needle into the right ventricle and apply gentle negative pressure to the syringe to fill the syringe with blood. Excessive negative pressure will collapse the chamber. The right atrium also works well for drawing blood, but the left side of the heart is more difficult.
   

Closed Chest Method

1. Have ready a syringe (3–10 ml) containing ~0.3 ml air and with a 20 gauge needle attached.
2. Make an incision in the skin and abdominal wall, caudal to the sternum.
3. Using a hemostat or thumb forceps applied to the xiphoid process, retract the sternum cranially until the apex of the heart is visible against the diaphragm.
4. Insert the needle through the diaphragm and into the heart, applying gentle negative pressure once the heart has been punctured, and reposition the needle as necessary until blood flows into the syringe. Avoid excessive negative pressure, as it will collapse the heart chamber onto the needle tip.