OXIDATION OF LOW-DENSITY-LIPOPROTEIN IN PATIENTS ON REGULAR HEMODIALYSIS

Patients undergoing chronic haemodialysis are known to have a high inc idence of premature atherosclerosis for reasons which have not been fu lly elucidated. The susceptibility of low density lipoprotein (LDL) to oxidation by copper ions in vitro is widely used as a measure of its atherogenicity in vivo. We measured the susceptibility of LDL to oxida tion using copper ions in haemodialysis patients and found, surprising ly, a markedly increased resistance to oxidation. The experiment was t herefore repeated using an alternative free radical generator, AAPH [2 ,2'-azobis-(2-amidinopropane hydrochloride)], to promote LDL oxidation ; using AAPH, the susceptibility to oxidation was similar in the dialy sis group compared to controls. Abnormal LDL composition in the dialys is patients was also demonstrated. We suggest that, in such situations , susceptibility of LDL to oxidation in vitro may be highly dependent on the biochemical method employed and therefore may not accurately re flect atherogenic risk.