A novel blood collection technique from the rat thoracic aorta: employing a diaphragm sac as a reservoir

Several blood withdrawal techniques are employed for biochemical research. However, these techniques fail to fulfil the desired requirement of blood volume. We invented the alternative method of blood collection through the thoracic aorta in an anesthetized rat. Under anesthesia, the rat was placed supine, and a transverse abdominal incision was made. The diaphragm was carefully cut, and a vertical thoracic incision was performed. The rat was held upright, creating a diaphragm sac, as a natural reservoir for blood collection. The thoracic aorta was identified and cut, allowing a large volume of blood to accumulate and be collected in sample tubes. The purity of the blood samples was determined using the plasma protein concentration, hemolysis index and lactate dehydrogenase (LDH) activity. A maximum blood volume of approximately 10–15 mL was successfully collected from the thoracic aorta using the diaphragm sac in a single rat. This method provided a higher blood yield compared to traditional techniques, such as retro-orbital bleeding, tail vein sampling, and cardiac puncture, all of which typically yield smaller volumes and require multiple collections. The blood collected using this method demonstrated comparable quality to that obtained via cardiac puncture, with no significant differences observed in plasma protein concentration, hemolysis index and LDH activity, supporting its suitability for high-quality plasma collection. Existing blood collection methods often fall short of volume requirements, leading to repeated needle and capillary use and causing animal stress. In contrast, the proposed method is simpler, designed for rats sacrificed post-procedure. The new blood collection method through the thoracic aorta efficiently provides large blood volumes, ideal for biochemical investigations.