Demonstration of prostaglandin activity in lungs of the rainbow lizard (Agama agama) by bioassay

Extracts and perfusate effluents of lungs of the rainbow lizard (Agama agama) were assayed for prostaglandin-like activity. Results of differential bioassay and thin-layer chromatography suggested that the prostanoid was predominantly PGE2-like. The mean PGE2-like content of 10 lizard lung extracts was 2.9 micrograms g-1 wet weight compared with 146 ng g-1 in rat lungs. Mechanical pressure applied to the lung during perfusion through the pulmonary vasculature provoked the release of large quantities of PGE2-like material. This release was blocked by fatty acid cyclooxygenase inhibitors. Compared with guinea-pig and rat lungs, lizard lungs exhibited a markedly low capacity for inactivating PGE2. In view of an apparently high prostaglandin-forming and a low inactivating capacity, we speculate that under certain circumstances, lizard lungs may release vasoactive substances into the circulation.