Dietary fat type and ambient oxygen tension influence pulmonary prostaglandin synthetic potential

Chronic hyperoxia produces pathological changes in lung which can be fatal. With an interest in delineating dietary factors which might affect the pulmonary response to hyperoxia, we fed rats a semi-synthetic diet containing polyunsaturated fatty acids (PUFA) as either 5% or 78% of the fat complement. The rats were exposed to pure oxygen at one atmosphere. Half the animals in each diet group were injected with aspirin during the hyperoxic exposure. Radioimmunoassay of lung prostaglandins (PG) F2alpha, E2 and E1 were performed at 0, 24, 48 and 72 hours. The major findings were: (1) Feeding the high PUFA diet elevated lung PG synthetic potential tenfold over that of low PUFA-fed animals. There was no effect of diet on mortality. (2) Hyperoxia significantly increased F2alpha-synthetic potential during the first 24 hours of hyperoxia and moderately increased the synthetic potential of E2 and E1. (3) Aspirin significantly depressed synthetic potential of all three PG prior to oxygen exposure but its effect was overcome during hyperoxia. Aspirin-injected rats showed 80% mortality in oxygen vs. 50% for saline controls.