HEPATIC AND RENAL PATHOLOGY OF INTRAPERITONEALLY ADMINISTERED MICROCYSTIN-LR IN RAINBOW-TROUT (ONCORHYNCHUS-MYKISS)

B. G. Kotak, S. Semalulu, D. L. Fritz, E. E. Prepas, S. E. Hrudey and R. W. Coppock. Hepatic and renal pathology of intraperitoneally admini stered microcystin-LR in rainbow trout (Oncorhynchus mykiss). Toxicon 34, 517-525, 1996.-In 26 hr laboratory trials a dose of 1000 mu g/kg m icrocystin-LR (MC-LR) caused 100% mortality in rainbow trout, while no mortality was observed at doses of 400 mu g/kg or less. The liver to body mass ratio increased in fish exposed to the toxin which was likel y due to water retention in the liver. In contrast to mammalian studie s, hemorrhage of the liver was rare in fish. Exposure to MC-LR caused widespread hepatocellular swelling and lysis of hepatocyte plasma memb ranes, resulting in liquifactive necrosis (organelles floating in a mi lieux of cellular debris). Kidney lesions in the fish consisted of coa gulative tubular necrosis with a dilation of Bowman's space. Lesions o bserved in the liver and kidney of fish exposed to MC-LR were consider ably different than those previously reported for mammals. Copyright ( C) 1996 Elsevier Science Ltd.