TOXICOKINETICS OF BREVETOXIN PBTX-3 IN THE GULF TOADFISH, OPSANUS-BETA, FOLLOWING INTRAVENOUS ADMINISTRATION

The toxicokinetics of brevetoxin [H-3]PbTx-3 were studied in the gulf toadfish (Opsanus beta) implanted with an indwelling cannula in the caudal vein. After an intravenous bolus injection (0.5-mu-g/kg), the concentration of [H-3]PbTx-3 in blood declined rapidly and triphasically with a terminal half-life of elimination of 29 min. The toxicokinetics of [H-3]PbTx-3 were best described by a threecompartment open model with the central compartment representing the blood of toadfish. One hour following [H-3]PbTx-3 administration, radioactivity was detected in all tissues examined, with the highest proportions in the muscle, intestine and liver (40.2, 18.5 and 12.4% of body burden, respectively). Through 96 h, levels of radioactivity in the liver remained relatively constant, while levels in bile, kidney and skin increased, and the amounts in all other tissues decreased. Extraction of toadfish bile by chloroform and subsequent thin layer chromatography, revealed the presence of both aqueous-soluble and organic-soluble metabolites of PbTx-3. The results are discussed in the context of potential mechanisms of metabolism and excretion, and the residence times of PbTx-3 in fish tissues vis a vis potential health risks.