IV. Tissue Origins of the Vasotropic Principles, VEM and VDM, Which Appear during Evolution of Hemorrhagic

Studies were carried out in (logs and rabbits subjected to hemorrhagic and tourniquet shock to determine the tissue origins of two newly described vasotropic principles, VEM and VDM. The vasoexcitor principle, VEI\, predominates in the blood during the initial compensatory stage and was traced to the kidney. The vasodepressor principle, VD-M, prevails during the decompensatory phase and w-as found to originate in the liver, skeletal muscle and spleen. During the decompensa-tory phase, there was a progressive deterioration of the hepatic mechanisms for inactivating VDMU. Sequential tissue hypoxia during shock is probably responsible for the formation of these vaso-tropic principles and for the deterioration of the hepatic VDi\I inactivation system. Special empha-sis is placed on the effects of local concentrations of VDMvwithin the liver and on the resultant diversion of blood from the general circulation into the splanchnic viscera. S TUDIES in this laboratory, over the past several years, have been concerned with the participation of specific humoral vasotropic factors in the deranged circulatory hemodynamics of experimental hemorrhagic and traumatic shock. These investigations have led to the development of a concept of experi-mental shock, especially with respect to the phenomenon of irreversibility, which has al-ready been presented in several publications of a descriptive character.1 2 It is the purpose of the present series of papers to provide the ex-perimental evidence from which this concept developed. When these studies were inaugurated the concepts of shock then current failed to provide an adequate explanation for many of th