抄録
Lung is not only a respiratory organ, but also a metabolic organ. Pulmonary vascular beds are extremely wide and this helps the lung to metabolite various vasoactive substances and to perform the gas exchange. Lungs can metabolite or inactivate PGE2, PGF2α, LTC4, LTD4, LTE4, serotonin, acetylcholine, bradykin, histamine and norepinephrine, and can produce histamine, serotonin, PAF, LTs, thromboxane A2 and various PGs. Percentage inactivation of PGs and LTs are closely dependent to the width of pulmonary vascular beds. The percentage inactivation showed a marked decrease by increasing the dose of administered vasoactive substances, and also showed a marked decrease by clumping the left pulmonary artery trunk or by infusing glass beads (100μ of diameter) into the pulmonary artery.
Chemical mediators, histamine and SRS-A can interact and regulate the release of other chemical mediator, and PAF accelerates the release of histamine, SRS-A, LTC4 from passively sensitized guinea pig lung tissue following the antigen challenge.
It is well known that cigarette smoking has diverse effects not only on the airway system but also on the pulmonary and systemic circulation.
