Cigarette smoke ventilation decreases thromboxane B2 metabolism in isolated rat lungs

3H-TxB2 was infused into the pulmonary circulation of isolated perfused rat lungs. The metabolites were analysed from the nonrecirculating perfusion effluent. When the lungs were ventilated with cigarette smoke the amount of unmetabolized TxB2 in the effluent was increased by 50%. The amount of the main metabolite was, however, not changed. The efflux of radioactivity from the lungs after a bolus injection of 3H-TxB2 was slower during cigarette smoke ventilation than during air ventilation. This suggests that cigarette smoke inhibits the enzymes metabolizing TxB2 rather than the pulmonary thromboxane uptake system.