アポリポ蛋白A-I isokbrmに関する臨床的研究

―肥満*, Probucol投与**, 運動による影響―

抄録

Apo A-I has been known to have five isoforms which can be separated by two-dimensional gel electrophoresis. The three acidic isoforms (A-I₀, A-I_-1, A-I_-2) are mature apo A-I consisting of 243 amino acids. The other two basic isoforms (A-I₊₂, A-I₊₁) are proapo A-I, having a six-amino-acid extension to the NH₂ terminal of the mature apo A-I.
In the present study, the patterns of apo A-I isoforms under three different conditions were examined. Firstly, the effect of weight reduction on the apo A-I isoforms of 11 normolipidemic obese women was investigated. Secondly, the effect of Probucol administration on the apo A-I isoforms of 15 hypercholesterolemic subjects was investigated. Finally, the apo A-I isoform pattern of 9 trained swimmers was compared with that of 7 sedentary controls.
Weight reduction of obese women caused proapo A-I decrease not only in relative percentage, but in the total amount. (significant only in HDL₃-A-I₊₂, 3.1±1.2 vs 2.3±0.5mg/dl, p>0.05) Mature apo A-I also tended to decrease in amount. Probucol administration caused significant increase of HDL₂-A-I₊₂ in relative percentage. (5.4±1.4 vs 6.6±1.7%, p>0.02). Mature apo A-I tended to decrease both in relative percentage and total amount. Swimmers' apo A-I isoform was high in the pro/mature ratio in HDL₃. (0.10±0.02) Significance was seen only in HDL₃-A-I₊₂. (5.9±1.0 vs 3.9±1.0%, p<0.01)
Apo A-I isoform pattern is thought to be influenced by at least three factors: synthesis and degradation of apo A-I and proapo A-I protease activity. The results of the present study suggest that the determination of apo A-I isoforms might provide crucial information about apo A-I metabolism.