INFLUENCE OF PLASMA PHYTANIC ACID LEVELS IN REFSUMS-DISEASE ON THE BEHAVIOR OF THE ERYTHROCYTE-MEMBRANE SODIUM-LITHIUM COUNTERTRANSPORTER

Background Abnormal behaviour of the erythrocyte membrane sodium-lithi um counter-transporter (SLC) is associated with plasma triglyceride co ncentrations. Refsum's disease is characterized by progressive neurolo gical dysfunction and accumulation of phytanic acid, an isoprenoid fat ty acid, in fat-containing tissues. Methods This study explored the ef fects of plasma phytanic acid on SLC kinetics in nine Caucasian patien ts with Refsum's disease and in age-and sex-matched Caucasian control subjects. Results A dose-dependent association was seen between counte rtransporter maximal velocity and phytanic acid content of low-density lipoprotein (LDL)-cholesterol (r=-0.61, r=-0.65 respectively; P=0.05, P=0.04) and high-density lipoprotein (HDL)-cholesterol (r=-0.81, -0.8 2 respectively; P = 0.005, P = 0.003). No significant association was seen with the sodium affinity of the transporter (r=-0.44, P = 0.20, f or LDL; and -0.43, P = 0.21, for high-density lipoprotein). Conclusion These findings suggest-that phytanic acid may alter the behaviour of the sodium-lithium countertransporter.