Effects of cigarette smoking on the function of metabolizing arachidonic acid and angiotensin I in the isolated perfused rat lungs.

The effects of acute and chronic cigarette smoking on the metabolism of exogenous arachidonic acid (AA) and angiotensin I (AI) in perfused isolated rat lungs were studied. The results showed that acute cigarette smoking did not alter the contents of 6-keto-PGF1 alpha (the stable metabolite of PGI2) and TXB2 (the stable metabolite of TXA2) in the effluent and the increment of pulmonary artery pressure (delta Ppa) caused by AA. The conversion of A I into A II was significantly increased (P < 0.01), while the delta Ppa induced by A I injection was obviously decreased as compared with controls (P < 0.05). After cigarette smoke exposure for 30 days, the delta Ppa caused by AA or A I did not differ from that of controls, but the contents of 6-keto-PGF1 alpha and A II increased more markedly than those in non-smoking rats (P < 0.05). It is suggested that acute and chronic cigarette smoking in rats can promote the lung function of converting A I into A II, chronic smoking can increase the lung function of metabolizing AA into PGI2.