[Vasodilating effect of leukotriene C4 and D4 by stimulation of prostacyclin synthesis]

Since the original discovery and structural characterization of leukotrienes, these substances have attracted considerable interest due to their numerous biological activities. It is known that these substances exert a short lasting vasoconstrictory and a longer lasting vasodilatory response. However, the cause of this biphasic response is not clear as yet. Human coronary artery segments synthesize about 50 pg PGI2/cm2/min in vitro under pressure perfusion. At concentrations ranging from 1 to 100 ng leukotrienes C4 and D4 cause a dose-dependent increase in PGI2 generation. Inhibition by acetylsalicylic acid and 15-hydroxyperoxyarachidonic acid indicates the mechanism to be mediated via the cyclooxygenase. It is, therefore, concluded that the capacity of leukotrienes C4 and D4 to stimulate PGI2 formation might play a key role during acute inflammation at the site of white blood cell accumulation.