[The role of the myocardial depressant factor in the pathogenesis of the shock].

Examination of the pathogenesis of shock has directed attention to the microcirculation, the kidneys, and the lungs. Today, apart from other tissues and organs, particularly the splanchnic organs, the pancreas is also incriminated. The lysosomes (also present in other tissues) and zymogen granules it contains are responsible, during the ischaemia and hypoxia typical of shock, for the instigation of a process of cell autolysis that releases enzymes and frequently toxic protein fragments into the bloodstream. These include myocardial depressant factor (MDF), whose physical, chemical and biological identification and rôle are now fairly clear. First described by Brand & Lefer in 1966, MDF has been explored by Lefer and other workers at both the experimental and clinical level. An account is given of the main researches that have led to the determination of the characteristics and action of MDF in numerous types of shock, the pattern of its formation, and the routes by which it is introduced into the circulation. Reference is made to work showing the close relation between MDF and the lysosomial hydrolases, and its biological effects on the whole animal, on isolated preparations, and in vitro. In addition to the myocardial depressant effect that has given it its name, MDF has been shown to provoke ischaemia of the splanchnic circulation and depression of the RES. The evidence on both sides is presented, including that derived from personal investigations of district haemodynamics in experimental shock. In substance, material is presented from which an objective approach can be taken to the cultural contribution of MDF in the matter of shock, its prospects, and its limitations.