Differences in Biological Activation of Arachidonic Acid in Perfused Lungs from Guinea Pig, Rat and Man

Arachidonic acid (AA) perfused through the pulmonary circulation of isolated lungs from guinea pig was metabolised to more myotropic metabolites than it was in rat or hjman lungs. There was more rabbit aorta contracting activity in effluent following AA in guinea-pig lungs than in rat or human lungs. This correlated with the amount of thromboxane B2-like material identified by t.l.c. following 14C-AA infusion. The release of cyclooxygenase products by guinea-pig SRS-A was observed only in guinea-pig lungs and not in rat or human lungs. The calcium ionophore A23187 released cyclo-oxygenase products from the lungs of all three species but rat and human lungs released less and required more ionophore for relase. There are important quantitative and qualitative differences in the activation of exogenous or endogenous AA between guinea-pig lungs and those from rat and human. The rat lung provides a better model than guinea-pig lung for AA metabolism in human lung.