IN-VIVO AND IN-VITRO INTESTINAL TRANSPORT OF H-3-MICROCYSTIN-LR, A CYANOBACTERIAL TOXIN, IN RAINBOW-TROUT (ONCORHYNCHUS-MYKISS)

The intestinal uptake of the tritiated form of the cyanobacterial hepa totoxin microcystin-LR (MC-LR) by rainbow trout (Oncorhynchus mykiss) was investigated in vivo and in vitro. Rainbow trout were administered a single dose of 1 mM H-3-MC-LR by oral gavaging. After 24 h, approxi mately 0.3% of the radiolabel delivered into the intestine was detecte d in the liver and muscle, but not the spleen or kidney. The distribut ion of radiolabel in these tissues was not affected by 10 mM of the bi le salt deoxycholate or 1 mM of 'cold' MC-LR. The in vitro intestinal transport of MC-LR from mu-osa to serosa was linear with respect to in testinal concentrations of MC-LR over a range of 1.6 mu M and 101 mM, and was not affected by the Na+/K+-ATPase inhibitor cuabain, suggestin g that a component of MC-LR transport across the intestine of rainbow trout may be passive. (C) 1998 Elsevier Science B.V. All rights reserv ed.