The effect of aspirin pretreatment on the fate of arachidonic acid in hamster isolated lungs.

The fate of exogenous arachidonic acid (AA) was investigated in isolated perfused lungs from hamsters, which were pretreated with aspirin in drinking water (0, 5, 50 or 500 mg/1) for one week. When 40 nmol of 14C-AA was infused in two minutes into the pulmonary circulation, the perfusion pressure increased. This pressor response was decreased by 50 mg/1 aspirin and was negligible after 500 mg/1. The amount of radioactivity was increased by aspirin pretreatment in the perfused lungs and decreased in the nonrecirculating perfusion effluent, which was collected for 6 minutes after the beginning of the AA infusion. The amount of unmetabolized free arachidonate was not changed significantly in the perfusion effluent or in the perfused lungs. The perfusion effluent was extracted with ethyl acetate first at pH 7.4 to extract unmetabolized AA, metabolites of lipoxygenase and HHT and then at pH 3.5 for prostaglandins and thromboxanes. The amounts of all arachidonate metabolites were decreased rather similarly by aspirin pretreatment. In the perfused lung tissue the amount of 14C-AA was increased by aspirin in phospholipids and in the triacylglycerol fraction of neutral lipids.