INCREASED NA-FIBROSIS( MG2+ ANTIPORT IN ERYTHROCYTES OF PATIENTS WITHCYSTIC)

Na+/Mg2+ antiport and Na+-independent Mg2+ efflux were investigated in erythrocytes of 41 patients with cystic fibrosis and 26 controls. Na-independent Mg2+ efflux was unchanged in cystic fibrosis, but a signi ficantly increased activity of Na+/Mg2+ antiport was detected (control : 0.16 +/- 0.02, cystic fibrosis: 0.39 +/- 0.06, Mg2+ efflux, mmol/30 min x 1 cells, mean +/- SEM, p < 0.01). An increased activity of Na+/M g2+ antiport was only found in patients with severe clinical symptoms. There was no correlation of the increased Na+/Mg2+ antiport to the dF 508 genotype. In a patient with increased Na+/Mg2+ antiport, the capac ity of this transport system was unchanged 14 weeks after double lung transplantation but reached control values after 53 weeks. The sweat o f cystic fibrosis patients with severe clinical symptoms showed a sign ificantly increased Mg2+ concentration (control (n = 12): 0.053 +/- 0. 08, cystic fibrosis (n = 9): 0.123 +/- 0.016 mmol/l, mean +/- SEM, p < 0.001).