THE FATE OF ADENINE NUCLEOTIDES IN THE PULMONARY CIRCULATION OF ISOLATED LUNG

¹ Department of Pharmacology, Institute of Basic Medical Sciences, Royal College of Surgeons of England, Lincoln's Inn Fields, London WC2A 3PN

The hydrolysis of ATP, ADP and AMP was studied in perfused isolated lungs from rats, hamsters, guinea-pigs and humaps. In rats, ATP and ADP at concentrations up to 1 mM were extensively broken down to AMP and AMP itself was more resistant to further hydrolysis. This pattern of metabolites was maintained in rat lung perfused with Krebs solution containing albumin. The effects of endogenous sex hormones on ADP metbolism were studied in lungs from female rats at different stages of the oestrous cycle. There were no cycle-related changes observed and in a comparison between sexes, only a small difference between males and females was apparent. Lung effluent from rat lungs exhibited a low level of ADPase activity. Although hamster lungs metabolized ADP to AMP as did rat lungs, lungs from guinea-pigs and humans metabolized ADP and AMP extensively to adenosine. This difference means that although all species exhibit the ability to inactivate pro-aggregatory ADP, the ability to form the anti-aggregatory adenosine from ADP in the pulmonary vasculature varies markedly between species.