MODULATION OF PULMONARY VASCULAR-RESISTAN CE AND EDEMA FORMATION BY SHORT-TERM INFUSION OF A 10-PERCENT FISH-OIL EMULSION

Background: The aim of this study was to investigate whether the pulmo nary response to inflammatory stimulation, resulting in increased vasc ular resistance and permeability, could be attenuated by short-term in fusion of triglycerides containing omega-3 fatty acids. With the conce pt of altering the composition of membrane phospholipids in such a man ner that stimulation resulted in the release of less vasoconstrictive and permeability-enhancing metabolites of eicosapentaenoic acid instea d of those of arachidonic acid (AA), the parenteral application of a l ipid emulsion prepared from fish oil (Omegavenos((R))) was tested in c omparison with a soy oil preparation (Lipovenos((R))). Methods: Isolat ed lungs from anesthetized rabbits were ventilated and recirculatingly perfused (200 ml/min) with 200 ml cell-free buffer solution to which either 2 ml saline (controls, n=6), 2 ml Lipovenos 10% (n=6) or 2 ml O megavenos 10% (n=6) were added. To study the possible metabolic altera tions in states of an enhanced AA turnover, lungs of each group were s timulated with smaller doses of A23187 (10(-8) M) during the 180-min l ipid perfusion period, followed by a 10 times higher calcium ionophore A23187 (10(-7) M) challenge after washing out the lipids by exchange of perfusion fluid. Pulmonary artery pressure (PAP) and the lung weigh t gain indicating edema formation were monitored, and eicosanoids were analyzed in samples of the perfusate. Results: Upon A23187 injection lung weight gain and PAP increase were significantly reduced (50%) in Omegavenos-perfused lungs in comparison with controls and Lipovenos tr eatment. The vascular reactions were accompanied by a shifting from LT C(4) to LTC(5) during and after Omegavenos perfusion. Conclusion: The data demonstrate that omega-3 fatty acids seem to be incorporated into the phospholipid pool of the pulmonary tissue, even after short-term infusion (3 h) resulting in an attenuated pressure reaction and edema formation due to an altered spectrum of metabolites in the case of inf lammatory stimulation.