A Study of Antifibrinolysin Activity

This report describes methods which have been developed in this laboratory for the determination of antifibrinolysin activity in plasma. Using these methods, studies have been made of the antifibrinolysin activity in the plasma of the alligator (Alligator inississippiensis), guinea pig (genus Cavia), cow (Bos taurus), rat (Rattus norvegicus, Sprague-Dawley strain), frog (Rana pipiens), man (white, male), cat (Felis domestica, dog (Canis familiaris, mongrel breeds), rabbit (genus Lepus, mixed strains), opossum (Didelphis virginiana), chicken (genus Gallus, Plymouth Rock), and pigeon (Columbia livia). With the exception of man, both sexes were represented but pregnant animals were not utilized in the sampling. Graphs are presented which indicate the relationships between plasma concentration (antifibrinolysin units) and the time required for the clots to dissolve. With the help of these graphs it is possible to measure the unit antifibrinolysin activity in a plasma sample from any of the species which have been studied. The terminology used in this report will be the one recently suggested by Loomis, George and Ryder (1) and by Astrup and Permin (2). Considerable confusion has existed in the past regarding nomenclature and we believe that a uniform terminology will assist greatly in the development of this field. Antifibrinolysin (Fibrinolysin Inhibitor [3], serum antitryptase [4], antiplasmin [5], serum antiprotease [6] ) is present in the plasma of all species which we have tested. It is not yet available in a pure state and therefore its chemical characteristics are unknown. This substance or substances in plasma inactivate fibrinolysin. It is not certain whether antifibrinolysin forms an inactive complex with fibrinolysin or whether the in-