CYSTIC-FIBROSIS AND PHOSPHATIDYLCHOLINE BIOSYNTHESIS

The cystic fibrosis (CF) gene defect may be associated with a defect i n membrane recycling. We have investigated the metabolism of the main constituent of plasma membrane, phosphatidylcholine (PC). In this stud y of platelets and fibroblasts, we show an increased uptake of choline into PC of CF cells as compared with normal cells, No accumulation of PC was seen. Other patients with respiratory disease (not CF) showed normal rates of incorporation of choline into platelet PC. Platelets f rom heterozygote individuals showed intermediate turnover rates of cho line incorporation into PC. The increase in choline incorporation into PC in CF platelets was not due to modified or increased sensitivity t o either cAMP or prostaglandin E(2). The total amount and the proporti ons of the major phospholipids in platelets of control and CF individu als were identical. These findings indicate an increased turnover rate of this phospholipid in CF cells rather than an increased net synthes is.