What is “Heparin”?

Abstract

“Heparin” has been and is still used with four different meanings, depending on the author: (1) any heat-stable naturally occurring anticoagulant activity (neutralized by protamine, etc.); (2) a sulfated mucopolysaccharide present in tissues, highly metachromatic, with a high critical electrolyte concentration, with mast cells; (3) a commercial drug of varying composition and activities; and (4) a sulfated mucopolysaccharide with distinctive chemical and biologic properties. I have discussed the problem of a term having different meanings in different disciplines (9). The four definitions of “heparin” are those of the hematologist, the histologist, the clinician-pharmacologist, and the biochemist. To our regret, the first definition is still found in the literature. The second definition will be applicable later in these proceedings. This portion of the conference is directed to the third and fourth definitions, and the third shades imperceptibly into the fourth. The basic difficulty for Drs. Jeanloz, Cifonelli, and Brozovic has been the relation in operational terms of these definitions. One must work with the “heparin” of the third definition. Does the heparin in the fourth definition exist? This question caused the controversy between Jorpes and Charles and Scott in 1937–1939, and it must still trouble any serious workers.