Leukotrienes as mediators of ischemia and shock.

Leukotrienes have been implicated as mediators of ischemia and shock. Recent evidence has been obtained supporting the four major criteria of acceptance of leukotrienes as mediators of shock, namely (a) increased concentration in body fluids during shock states, (b) ability to exert significant pathophysiologic effects which aggravate ischemia and shock, (c) amelioration of the shock state by leukotriene synthesis inhibitors and leukotriene receptor antagonists, and (d) production of a shock-like state by exogenous administration of leukotrienes. In conclusion, both LTB4 and the peptide leukotrienes (e.g. LTC4, LTD4 and LTE4) also known as the slow reacting substance of anaphylaxis (SRS-A) can be considered as mediators of ischemia and shock. Although difficulties exist with measuring leukotrienes in circulating blood and in obtaining long lasting selective blockers of leukotriene synthesis, innovative experiments measuring leukotrienes in bile and other body fluids and in employing specific leukotriene receptor antagonists have helped in assessing the significance of the leukotrienes in shock states. Additional studies are necessary to evaluate these findings in perspective, and to compare and contrast the role of leukotrienes to that of other vascular mediators including prostaglandins and thromboxanes, as well as non-eicosanoids including serotonin, histamine, angiotensin II and vasopressin, all of which can play a mediator role in ischemia and shock states. Further clarification of these issues promises to open exciting new chapters in shock research.