title: A fluorimetric method based on changes in membrane potential for screening paralytic shellfish toxins in mussels.
abstract: To prevent the consumption of bivalves contaminated with paralytic shellfish poisoning (PSP), toxin levels in seafood products are estimated by using the official mouse bioassay. Because of the limitations of this bioassay other methods of monitoring toxins are clearly needed. We have developed a test to screen for PSP toxins based on its functional activity; the toxins bind to the voltage-gated Na+ channels and block their activity. The method is a fluorimetric assay that allows quantitation of the toxins by detecting changes in the membrane potential of human excitable cells. This assay gives an estimate of toxicity, since each toxin present in the sample binds to sodium channels with an affinity which is proportional to its intrinsic toxic potency. The detection limits for paralytic shellfish toxins were found to be 1 ng saxitoxin equivalents/ml compared to the regulatory limit threshold of 400 ng/ml (equivalent to 80 microg/100 g) used in most countries. Our results indicate that this fluorescent assay is a specific, very sensitive, rapid, and reliable method of monitoring PSP toxin levels in samples from seafood products and toxic algae.
authors.affiliation: Departamento de Farmacología, Facultad de Veterinaria de Lugo Universidad de Santiago de Compostela, 27002 Lugo, Spain.
authors.forename: M C
authors.initials: MC
authors.lastname: Louzao
authors.forename: M R
authors.initials: MR
authors.lastname: Vieytes
authors.forename: J M
authors.initials: JM
authors.lastname: Baptista de Sousa
authors.forename: F
authors.initials: F
authors.lastname: Leira
authors.forename: L M
authors.initials: LM
authors.lastname: Botana
mesh_terms: D000818:Animals; D001681:Biological Assay; D049872:Bivalvia / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D005470:Fluorometry / Q000379:methods*; D005506:Food Contamination / Q000032:analysis; D006096:Gramicidin / Q000494:pharmacology; D006801:Humans; D008387:Marine Toxins / Q000032:analysis*; D008564:Membrane Potentials; D051379:Mice; D009447:Neuroblastoma / Q000378:metabolism; D011869:Radioligand Assay; D015203:Reproducibility of Results; D012530:Saxitoxin / Q000031:analogs & derivatives / Q000032:analysis; D012680:Sensitivity and Specificity; D012758:Shellfish; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013997:Time Factors; D014407:Tumor Cells, Cultured; D014701:Veratridine / Q000494:pharmacology
chemical_list: D008387:Marine Toxins; D006096:Gramicidin; D012530:Saxitoxin; D014701:Veratridine; C013007:gonyautoxins