The effects of exogenous platelet activating factor (PAF), BN52021 (an antagonist of PAF receptor), indomethacin and verapamil on the production of TxA2, PGI2 and activity of Ca(2+)-ATPase were investigated in rabbit intra-pulmonary smooth muscle cells (PASMCs). The results were as follows: (1) Under basic condition, active AA metablism was present in PASMCs. (2) Significant increase of TxA2 and PGI2 but not their ratio may result from binding of PAF receptor and activation of cyclooxgenase. (3) Activity of Ca(2+)-ATPase could be inhibited by exogenous PAF. (4) The inhibitory effect of PAF on PASMCs Ca(2+)-ATPase could be reversed by verapamil.