Abnormal fatty acid composition and impaired oxygen supply in cystic fibrosis patients.

Impaired oxygen supply and deteriorating health, in cystic fibrosis patients, correlates with abnormal changes in the fatty acid composition of blood lipids. As the proportion of oleates increases and that of linoleates decreases, erythrocyte membrane interference with the formation of intracellular oxyhemoglobin increases and arterial oxygen pressure decreases. The physical-chemical basis for these changes seems to be that oleic and linoleic acid differ in their ability to undergo reversible oxygenation in response to changes in oxygen pressure. The oxygen complex of linoleic acid dissociates at relatively high pressures, whereas that of oleic dissociates only at low pressures. Accordingly, excessive substitution of oleic for linoleic acid in membrane lipids would be expected to decrease the intracellular oxygen pressure to a level where hemoglobin oxygenation and any other oxygen-requiring processes would be impaired.