Comparative lipogenic activities offish tissue, lipolytic activity of mesenteric fat and mode of intestinal lipid release into blood were investigated in a variety of Amazon fish. Small catfish were injected intramuscularly with [1-l4C]acetate, killed at intervals, and the lipid radioactivity of 11 separate tissues determined. In 6- and 18-h fish, the heart, eyes, dark muscle, and white muscle synthesized negligible lipid relative to the other tissues. Acetone powders of Triportheus sp, mesenteric fat contained high amounts of triglyceride lipase activity (120 nmol fatty acid release-d/min per milligram protein). The activity exhibited a pH optimum of 8.0 and was not activated by albumin, bile salts, or divalent salts nor inhibited by 1 M NaCl. Characteristics of the observed activity are identical with those of mammalian pancreatic lipase. Hoplias malabaricus were fed [1-14C]oleic acid and a chronic indwelling catheter was placed in the dorsal aorta for blood sampling. Based on the distribution of radioactivity among blood lipid classes, it is suggested that dietary lipid enters fish circulatory systems both as free fatty acid and as lipoproteins.
Metadata description of the AMAZON FISH database
