Corticotropin-induced reduction of plasma lipoprotein(a) concentrations inhealthy individuals and hemodialysis patients: Relation to apolipoprotein(a) size polymorphism

Lipoprotein(a) [Lp(a)] a strong independent cardiovascular risk factor, con sists of the unique apolipoprotein(a) [apo(a)] covalently linked to a low-d ensity lipoprotein particle. Apo(a) contains a widely differing number of t he plasminogen-like kringle IV, a size polymorphism that is codominantly in herited. In addition to powerful genetic control, renal failure is known to influence the plasma Lp(a) concentration. There is still a lot to be learn ed about the mode and site of catabolism of Lp(a), and there is no readily applicable Lp(a)-lowering treatment available. Therefore, it was of Interes t to study further the Lp(a)-lowering effect of corticotropin (ACTH) that h as been demonstrated in small studies. The main purpose of the present stud y was to investigate the influence of ACTH on different apo(a) isoforms, Sh ort-term treatment with ACTH decreased the plasma Lp(a) concentration in al l 26 study participants. The two study groups (12 healthy individuals and 1 4 hemodialysis patients) responded similarly, with a median decrease in pla sma Lp(a) of 39% and 49%, respectively in subjects with two clearly separab le apo( a) bands, apo(a) phenotyping and densitometric scanning of the band s before and after treatment with ACTH revealed a change in the proportion of apo(a) isoforms, ie, a shift toward the isoform with lower molecular wei ght. This was observed in seven of nine investigated subjects (four of five healthy individuals and three of four hemodialysis patients). Copyright (C ) 1999 by W.B. Saunders Company.