PREFERENTIAL INFLUX AND DECREASED FRACTIONAL LOSS OF LIPOPROTEIN(A) IN ATHEROSCLEROTIC COMPARED WITH NONLESIONED RABBIT AORTA

The aim was to investigate the atherogenic potential of lipoprotein(a) (Lp(a)) and to further our understanding of the atherogenic process b y measuring rates of transfer into the intima-inner media (i.e., intim al clearance) and rates of loss from the intima-inner media (i.e., fra ctional loss) of Lp(a) and LDL using cholesterol-fed rabbits with nonl esioned (n = 13) or atherosclerotic aortas (n = 12). In each rabbit, I -131-Lp(a) (or I-131-LDL) was injected intravenously 26 h before and I -125-Lp(a) (or I-125-LDL) 3 h before the aorta was removed and divided into six consecutive segments of similar size. The intimal clearance of Lp(a) and LDL was similar and markedly increased in atherosclerotic compared with nonlesioned aortas (ANOVA, effect of atherosclerosis: P < 0.0001). Fractional losses of labeled Lp(a) and labeled LDL in athe rosclerotic aorta were on average 25 and 43%, respectively, of that in nonlesioned aortas (ANOVA, effect of atherosclerosis: P < 0.0001). Fr actional loss of Lp(a) was 73% of that of LDL (ANOVA, effect of type o f lipoprotein: P = 0.07). These data suggest that the development of a therosclerosis is associated with increased influx as well as decrease d fractional loss of Lp(a) and LDL from the intima. Accordingly, Lp(a) may share with LDL the potential for causing atherosclerosis.