The role of blood vessels in the bioconversion of leukotrienes in the pig.

Porcine pulmonary artery has the ability to convert leukotriene C4 (LTC4) to LTD4 and then to LTE4. In this vessel, there appears to be no further metabolism beyond LTE4. LTC4 (1 nM) is converted rapidly to LTD4, whereas the conversion of LTD4 to LTE4 is somewhat slower. The conversion of LTC4 to LTD4 is inhibited by the gamma-glutamyl transpeptidase inhibitor, serine-borate (45 mM). The conversion of LTD4 to LTE4 is inhibited by the aminopeptidase inhibitor, L-cysteine (10 mM). LTB4 did not appear to be metabolized by porcine pulmonary artery. These results suggest that the vessel wall may play a role in the early stages of leukotriene metabolism.