魚類における脂質の運搬機構に関する研究

抄録

In mammals, absorbed micelles are resynthesized in the epithelial cells of the intestine and transported as chylomicrons through the lymphatic route, then as various lipoproteins in the circulatory system. It is rather difficult to draw conclusions about the dynamic processes involved in the absorption and transport of lipids, since there are few studies on these processes in fish.
Carp treated with dorsal aorta cannulation, fed or starved for 3 weeks, were force-fed by catheter with 40 μCi of [1-¹⁴C] palmitic acid or -tripalmitin dissolved in 0.15ml of carp lipids and chased with 0.2ml of the cold lipids. From the cannulated tube, 0.8ml of blood was collected at various intervals after feeding. The disc electrophoresis pattern of carp blood plasma shows three main lipoprotein bands when prestained with acetylated Sudan black B: Band I (albumin lipid complex), Band II (near α₂-lipoprotein) and Band III (near β-and pre-β-lipoproteins of human plasma). Incorporation of palmitic acid into plasma lipid classes in starved fish was markedly characterized by the initial appearance within 1/2-3hr of FFA associated mainly with Band I followed by gradual increases in TG and PL later. Under normal conditions, high levels of FFA appeared; however, TG associated with Bands III and I appeared distinctly only after 6-12hr. In the case of tripalmitin feeding, FFA appeared first, the incorporation being moderate but constant, followed by TG (after 3hr) as the major lipid constituent associated first with Band III, which seemed to be converted to Band I after 6hr.
It can be pointed out from these results that the mammalian lipid transport mechanism is not applicable to fish; instead, Band I associated mainly with FFA plays an important role in fish lipid transport.