Biological Half-Life, Organ Distribution and Excretion of 125I-labelled Toxic Peptide from the Blue-green Alga Microcystis aeruginosa

Abstract

M. aeruginosa is a bloom-forming cyanobacterium which is common in fresh-water lakes. It contains a potent hepatotoxin which when purifed has been shown to be a heptapeptide of molecular weight 1019. The toxin was iodinated with 1251 using the lactoperoxidase method, the labelled toxin administered iI).travenously to adult female rats and the half-life and organ distribution measured. The blood half-life after redistribution into extracellular pools was 42 min. The liver and kidneys showed accumulation of 21�7 � 1�1 and 5�6 � 0�2% of the dose respectively after 30 min. Little accumulation was observed in other organs and tissues. Small-intestinal contents and urine contained 9�4 � 6� 1 and 2�9 � 1'2% of the dose respectively after 120 min. It was concluded that the liver is the main target organ for both accumulation and excretion of the toxin.