A method for large volume blood sampling and transfusion in rats

A new protocol that makes it feasible to withdraw large volumes of whole blood from an individual rat within 1 h or less is described. This method involves the use of indwelling catheters for withdrawal of blood from the inferior vena cava with concurrent isovolemic replacement of whole blood into the superior vena cava. Simultaneity of the transfusion and withdrawal, strict equality of volumes, and a smooth exchange of blood are assured by the use of separate channels of the same multiple-channel peristaltic pump for withdrawal and replacement. Validation experiments using both anesthetized and unanesthetized rats indicate that several responses remain essentially undisturbed during large volume blood sampling; these parameters include blood pressure, heart rate, hematocrit, plasma hormones including insulin and glucagon, plasma glucose levels, and feeding behavior. Considerations of technical and physiological limitations of the protocol, including choice of catheters and catheter placement, pump, sampling parameters, and obtaining donor blood, are discussed.