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Abstract:
Acid extracts of calf lung have been found to contain low-molecular-weight factors which increase the permeability of the microcirculation when injected into the skin of rats. These factors, which were present in very low levels in aqueous extracts, were purified by gel filtration and ion-exchange chromatography. High-voltage paper electrophoresis revealed two active compounds with mobilities identical to the polyamines spermine and spermidine. Authentic samples of these compounds were as active in the "blueing" reaction as the isolated compounds. The permeability activity of both the isolated factors and the synthetic ones was inhibited by pepstatin and by pretreatment of the animals with pyrilamine maleate. If the normally low extracellular levels of these polyamines is increased by tissue damage, they could increase vascular permeability within the lung by releasing histamine from adjacent mast cells.