title: The uptake of the cyanobacterial hepatotoxin microcystin by isolated rat hepatocytes.
abstract: Microcystin-YM a cyclic heptapeptide hepatotoxin isolated from the cyanobacterium Microcystis aeruginosa was radiolabeled with 125I, and used to investigate the uptake of the toxin by freshly isolated rat hepatocytes. The uptake was temperature dependent with apparent activation energy of 18 kcal/mole (77 kJ/mole) for the initial rate of uptake. Uptake of non-toxic (10-20 nM) doses of microcystin by hepatocytes continued with time, the intracellular to extracellular distribution ratio for the toxin was 70 at 60 min for 10(6) cells/ml. Uptake of higher doses of microcystin (100 nM and more) stopped when the cells blebbed: a toxic response of hepatocytes to microcystin. Uptake of microcystin by hepatocytes was inhibited 70-80% by the addition of 10 microM sodium deoxycholate or bromsulphthlein, compounds that protect hepatocytes from the toxic effects of microcystin.
authors.affiliation: Department of Biochemistry, Microbiology, and Nutrition, University of New England, Armidale, NSW, Australia.
authors.forename: M T
authors.initials: MT
authors.lastname: Runnegar
authors.forename: R G
authors.initials: RG
authors.lastname: Gerdes
authors.forename: I R
authors.initials: IR
authors.lastname: Falconer
mesh_terms: D000818:Animals; D001427:Bacterial Toxins; D002478:Cells, Cultured; D000458:Cyanobacteria; D000087522:Cyanobacteria Toxins; D003840:Deoxycholic Acid / Q000494:pharmacology; D008099:Liver / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008387:Marine Toxins / Q000378:metabolism* / Q000633:toxicity; D052998:Microcystins; D010456:Peptides, Cyclic / Q000378:metabolism* / Q000633:toxicity; D051381:Rats; D011919:Rats, Inbred Strains; D013448:Sulfobromophthalein / Q000494:pharmacology; D013696:Temperature
chemical_list: D001427:Bacterial Toxins; D000087522:Cyanobacteria Toxins; D008387:Marine Toxins; D052998:Microcystins; D010456:Peptides, Cyclic; D003840:Deoxycholic Acid; D013448:Sulfobromophthalein; C068747:microcystin YM