Differentiation of the in Vivo and in Vitro Actions of Tissue Extracts.

Abstract

In our earlier work 1 , 2 on tissue extracts, we found them active in promoting clotting of the blood in vitro or when intravenously injected, and also when administered to animals or man subcutaneously, intraperitoneally or orally during fasting conditions. During those studies we were dealing with fresh extracts or freshly purified fractions. More recently we have noticed that certain batches of tissue fibrinogen, after weeks of storage, lose entirely their effectiveness on intraperitoneal injections into animals, although they retain their full activity in vitro. Other batches made apparently in the same manner, are active with all forms of administration.

This raises the question as to whether we are dealing with 2 different actions of tissue fibrinogen, one of which is destroyed on standing, or whether 2 separate coagulants are present, one acting only when added directly to blood, and the other capable of accelerating clotting after absorption into the blood through the intestine or peritoneum. We offer evidence here that there are 2 distinct substances of this nature existing in crude tissue extracts or fresh preparations of tissue fibrinogen.

Healthy rabbits of about 4 pounds body weight, and fasted for 24 hours, were used for the injection tests. Two rabbits were used for the testing of each sample and for control in each series. In cases of any considerable disagreement in the results for a given test, a second 2 rabbits were used in similar fashion. Blood was carefully withdrawn from the heart in oiled syringes just prior to the injections and again one hour afterward.