Influence of tocopherol,its chromane compound,phytyl chains and superoxide dismu8tase on increased vascular resistance and permeability due to arachidonate metabolism in isolated rabbit lung

In the model of isolated, ventilated rabbit lungs, perfused with isoionic and isooncotic fluid, the addition of arachindonic acid to the perfusion fluid or the liberation of arachidonic acid by the Ca-ionophore A 23187 results in an increase in pulmonary vascular resistance and permeability. The former can be ascribed to cyclooxygenase products, the later to lipoxygenase products of arachidonic acid. The effects of α-tocopherol, its chromane compound, α-tocopherolquinone, phytol, 2-methyl-1,4-napthoquinone, 2-methyl-3-phytyl-1, 4-naphthoquinone and of superoxide dismutase (SOD) on the increase in pulmonary vascular resistance and permeability was investigated. A membrane effect of the phytyl side chain and an antioxidative effect of the chromane compound can be distinguished: phytol increases the arachidonate-induced rise of pulmunary vascular resistance and permeability, whereas the chromane compound decreases both to a large degree. Methyl-phytyl-naphthoquinone and methyl-naphthoquinone gave equivalent results. SOD decreases the enhanced vascular resistance and the vascular leakage. The possibility of antioxidative therapy in acute pulmonary lesions with vascular leakage and increased vascular resistance is discussed.