Comparative hematology and coagulation: studies on rodentia (rats).

Blood from adult male Wistar rats clotted rapidly in glass or siliconized tubes; the clots retracted and did not lyse. The serum prothrombin, plasma prothrombin and activated partial thromboplastin times were shorter than those of normal humans. In contrast, the thrombin and reptilase times were longer than those of normal human plasma, due apparently to the presence of a low-grade thrombin inhibitor in rat plasma. Coagulation factors, X, VIIIR:vW and IX assayed lower in rat than human plasma, while factors VIII:C and anti-thrombin III were higher. Values for other coagulation factors (II, V, VII, XI, XII and Fletcher) fell within the human range. Platelets were small and numerous. They aggregated well with ADP but poorly or not at all with collagen, ristocetin, thrombin, epinephrine, arachidonic acid and pig or bovine plasmas. Leukocytes numbered 4-8 X 10(3) cells/mm3, a near human range and were predominantly lymphocytic. Erythrocytes were small (MCV = 56-60 fl) and numerous (5.5-6.4 X 10(6) cells/mm3).