The effects of leukotrienes, thromboxane A2 and phospholipase A2 on human, porcine and guinea pig lung parenchyma.

A comparison was made of the contractions, induced by LTD4, histamine and phospholipase A2 in parenchymal strips of guinea pig (GPLP), porcine and human lung in a cascade superfusion system. The effects of LTD4 and phospholipase A2 on the release of TxA2 in these tissues and of TxA2, 5-HT and acetylcholine on the GPLP were also determined. In the GPLP strip, the LTC4-induced contractions are due for +/- 80% to the release of TxA2 and for +/- 20% to the direct effect of LTC4. The guinea pig tissue displayed the highest sensitivity towards all substances, except to the contraction induced by histamine, which was most effective in the porcine tissue. Low activities were found in the human tissue in all tests. The reason for these effects may be a difference in activities or number of cell types which participate in the reactions leading to the contractions.