抄録
We serially examined changes of blood chemistry and urinary constituents in association with longterm semi-starvation therapy (400kcal/day) for obesity. We found a new phenomenon that platelet aggregability increased after semi-starvation therapy. To clarify the mechanism of the increase of platelet aggregability we performed several experiments. The results are as follows:
(1) There was a weak negative correlation between the difference before and after semi-starvation therapy in platelet aggregability (ADP-induced platelet aggregation) and that in the plasma free fatty acid (FFA)/albumin ratio. However, the correlation did not seem to have a cause and effect relationship.
(2) When a low dose of norepinephrine was continuously infused into healthy subjects, the plasma FFA concentration increased in all subjects, but platelet aggregability did not change consistently.
(3) It was suggested by in vitro experiments, in which platelets obtained from the obese patient subjected to semi-starvation therapy were suspended in plasma obtained from the healthy subject and vice versa, that there are some factors in plasma which increase platelet aggregability.
(4) There was a more marked increase of platelet aggregability in obese patients who showed a more marked decrease in the ratio of eicosapentaenoic acid (EPA)/arachidonic acid (AA) and/or EPA+decosahexaenoic acid/AA after semistarvation therapy.
From the above-mentioned results, we concluded that the increase of platelet aggregability in obese patients after long-term semi-starvation therapy might be due to the increase in the concentration of the proaggregator, AA, in relation to the disaggregators, ω-3 polyunsaturated fatty acids (EPA and DHA). On the other hand, the increase in plasma FFA concentrations observed after the therapy did not seem to contribute to the increase of platelet aggregability after the therapy.
