Monohydroxyeicosatetraenoic acids (5-HETE and 15-HETE) induce pulmonary vasoconstriction and edema

Abstract

5-, 15-, and 12-HETE (monohydroxyeicosatetraenoic acids) are products of the lipoxygenation of arachidonic acid. We investigated their role as possible mediators of pulmonary vasoactivity and pulmonary edema. Pulmonary artery pressure (P(pa)), capillary pressure (P(cap)), the change in lung wet weight (Δwt) from baseline, and capillary filtration coefficient (K(f)) (as a measure of vascular permeability) were determined following an intravenous injection of each moni-HETE in lungs perfused at constant flow with either a phosphate-buffered Ringer's-albumin solution (PBR) or diluted blood. Injection of 2 μg of each compound into the pulmonary artery of lungs perfused with either PBR or diluted blood did not produce any effect. However, in PBR-perfused lungs, 4 μg 15-HETE induced increaes in P(pa), P(cap), and lung wet weight (p < 0.05), which were greater than the increases observed after 4 μg-5-HETE. K(f) increased following both 5- and 15-HETE. The pulmonary vasoconstrictor and edemagenic responses were attenuated by increasing perfusate albumin concentration from 0.5 to 1.5 g%. In contrast, 12-HETE (4 μg) had no effect on these parameters. In blood-perfused lungs, the pulmonary vascular responses to all HETE compounds (4 μg) were attenuated. In both Ringer's-albumin-perfused and blood-perfused lungs, the relative magnitude of the hemodynamic and fluid filtration responses to each moni-HETE were as follows: 15-HETE>5-HETE>12-HETE. In conclusion, the pulmonary vasoconstrictor and edemagenic effects of 5- and 15-HETE occur independently of blood-formed elements. 15-HETE causes greater pulmonary vasoconstriction and edema than 5-HETE. Both 5- and 15-HETE induce pulmonary edema, probably as a result of increased lung vascular permeability. The results indicate that 5- and 15-HETE are potent pulmonary inflammatory mediators.