Heat shock has a profound influence on the metabolism and behavior of eukaryotic cells. We have examined the effects of heat shock on the release from cells of arachidonic acid and its bioactive eicosanoid metabolites, the prostaglandins and leukotrienes. Heat shock (42-45 degrees) increased the rate of arachidonic acid release from human, rat, murine, and hamster cells. Arachidonate accumulation appeared to be due, at least partially, to stimulation of a phospholipase A2 activity by heat shock and was accompanied by the accumulation of lysophosphatidyl-inositol and lysophosphatidylcholine in membranes. Induction of arachidonate release by heat did not appear to be mediated by an increase in cell Ca++. Stimulation of arachidonate release by heat shock in hamster fibroblasts was quantitatively similar to the receptor-mediated effects of alpha thrombin and bradykinin. The effects of heat shock and alpha thrombin on arachidonate release were inhibited by glucocorticoids. Increased arachidonate release in heat-shocked cells was accompanied by the accelerated accumulation of cyclooxygenase products prostaglandin E2 and prostaglandin F2 alpha and by 5-lipoxygenase metabolite leukotriene B4. Elevated concentrations of arachidonic acid and metabolites may be involved in the cytotoxic effects of hyperthermia, in homeostatic responses to heat shock, and in vascular and inflammatory reactions to stress.