[abstract] DIETARY FAT AND THE ROLE OF PROSTAGLANDINS IN THE DEVELOPMENT OF PULMONARY OXYGEN TOXICITY

Abstract

As part of a program to evaluate the influence of various dietary constituents on susceptibility to pulmonary oxygen toxicity, male weanling mice and rats were fed a semi-synthetic diet, similar to that of the average American male, containing varying levels of polyunsaturated (PUFA) or saturated (SAT) fatty acids and then exposed to 1ATA pure oxygen. Mice fed 4 percent or 21 percent fat by weight (SAT/PUFA=1.5) showed no significant differences in mortality after 2, 4, 8 or 16 weeks of feeding. Rats fed diets containing 57, 11 percent or 20 percent fat (SAT/PUFA=1.5) for four weeks demonstrated an inconsistent pattern of mortality as a function of dietary fat content with those fed 11 percent most susceptible and those fed 20 percent least susceptible to toxicity. Rats fed diets containing 20 percent fat as safflower oil (PUFA) or beef tallow (SAT) for four weeks did not have significantly different rates of poisoning after 24, 48 or 60 hours of oxygen exposure as evidenced by protein and uronic acid contents of endobronchial washes. However, animals fed either diet and injected with aspirin, an inhibitor of prostaglandin synthetase, during oxygen exposure, exhibited an accelerated rate of pulmonary poisoning when compared to saline-injected controls. Analyses of lung tissue for prostaglandins El, E2 and F2 confirmed their reduced levels in aspirin-treated animals. We conclude that lung prostaglandin production plays a role in relative susceptibility to pulmonary oxygen toxicity but that the amount and type of dietary fat, containing the prostaglandin precursor arachidonic acid, does not appreciably influence their production or the response to oxygen exposure.