KINETICS OF DISTRIBUTION OF MICROCYSTIN LR IN SERUM AND LIVER CYTOSOLOF MICE - AN IMMUNOCHEMICAL ANALYSIS

The kinetics of distribution of microcystin LR (MCYST-LR) in the serum and liver of mice dosed with the toxin (35 mu g/kg) was analyzed by a direct competitive ELISA that has an analytical recovery of 67-109.9% of the toxin added to serum and liver cytosol (1-100 ng/mL). MCYST-LR was detected in serum (7.8 ng/mL) and liver (45 ng/mL) 15 min postinj ection and peaked at 2 h (62.7 ng/mL) in serum and at 12 h (250.5 ng/m L) in liver cytosol. A considerable amount of toxin was still found in serum (37.5 ng/mL) and cytosol (228.6 ng/mL) at 24 h postinjection. B etween 15 min and 24 h, approximately 4.4-35.2% and 16-89.5% of the in jected MCYST-LR was found in serum and liver cytosol, respectively. Re duced [H-3]MCYST-LR was used simultaneously with the ELISA analysis. A n excellent correlation (r = 0.99 at p < 0.0001) between data obtained from both methods was found. The presence of MCYST-LR in liver cytoso l was also confirmed by immunochromatography, which detected 98% of to xin injected into the HPLC column. An immunoreactive peak (shoulder) w as also found. In vitro analysis of protein phosphatase 2A activity of liver cytosol revealed that the enzyme activity started to decrease a t 1-2 h postinjection. Maximum decrease in enzyme activity occurred at 6-12 h after the animal received the toxin.