Thromboxane may be important in the organ damage and hypotension of malaria

Generalized circulatory changes, manifesting as pulmonary oedema, acute renal failure, liver damage and severe hypotension, are well recognized aspects of acute falciparum malaria. The organ pathology is thought to be associated with a restricted local blood flow. These aspects of falciparum malaria are strikingly analogous to the shock syndrome which follows trauma, the injection of indotoxin, or some bacterial infections. Two of the cyclooxygenase products of arachidonic acid, thromboxane A2 and prostacyclin, acting through their opposing effects on vasoactivity and platelet aggregation, are emerging as the major controlling influences of vascular homeostasis. The effects of thromboxane, which constricts blood vessels and aggregates platelets, appear to dominate during traumatic or endotoxic shock. Thus thromboxane is potentially one of the main mediators of endotoxicity, and as such, from our previously published model, is likely to be important in the pathogenesis of the circulatory disturbances seen in acute malaria. This suggestion is consistent with earlier evidence that the autonomic nerve supply and bradykinin may have an important role in the pathogenesis of the haemodynamic changes in this disease. It also implies that pharmacological antagonists of thromboxane may provide useful specific therapy for the main life-threatening aspects of acute falciparum malaria.