BILIARY-EXCRETION OF BIOCHEMICALLY ACTIVE CYANOBACTERIA (BLUE-GREEN-ALGAE) HEPATOTOXINS IN FISH

Previous reports demonstrated that microcystin and related cyanobacter ia polypeptides are rapidly cleared from plasma and accumulate in live r tissue. In the present study, we have used their ability to inhibit protein phosphatases to show that these cyanobacteria hepatotoxins are excreted into the bile of experimentally poisoned rainbow trout. At v arious times after oral administration of hepatotoxic Microcystis aeru ginosa, bile samples were analysed for microcystin content by methanol extraction and protein phosphatase assays. An inhibitory principle th at specifically suppressed protein phosphatase activity was detected i n all bile samples removed between 1 and 72 h after oral exposure to t oxic algae. These results indicate that biochemically active microcyst in molecules are excreted into the biliary tract of poisoned fish.