The content of stable metabolites of prostacyclin and thromboxane A2 in the rabbit myocardium in normal conditions and after single izadrin injection (comparison of survived and dead animals) has been comparatively analyzed. It has been shown that in all the cases izadrin injection induces the synthesis of these prostaglandins. But the cases with lethal outcome are characterized by predominance of the thromboxane-synthetase activity. The revealed peculiarities of prostaglandins synthesis in myocardium need experimental check on the isolated heart.