title: In vitro effects of yessotoxin on a primary culture of rat cardiomyocytes.
abstract: Oral administration of yessotoxin (YTX) has been reported to induce ultrastructural alterations in rodent cardiac muscle. To study its effects on various fundamental aspects of cardiac muscle cells activity, that is, cell beating, Ca(2+) and cyclic adenosine 3',5'-monophosphate (cAMP) levels, as well as cell vitality, a primary culture of rat cardiomyocytes was used. Patch-clamp recordings, Ca(2+) imaging, and cAMP assays were performed on cultured cardiomyocytes to characterize YTX effects on the cell beating frequency. 3-(4,5-Dimethylthiazole-2-yl)-2,5-biphenyl tetrazolium bromide (MTT) and sulforhodamine B (SRB) tests were carried out to determine its effect on cardiomyocytes viability. Videoimaging techniques showed a time- and concentration-dependent reduction in the beating frequency after 1, 5, and 24 h incubation with YTX (0.1-1 microM). This effect was neither associated to the uncoupling between the membrane electrical activity and Ca(2+) release from intracellular stores nor to the impairment of the mechanisms controlling the Ca(2+) homeostasis. In addition, 1 microM YTX did not modify basal cAMP levels in cardiomyocytes. MTT and SRB assays revealed that incubation of cardiomyocytes with YTX (0.01-1 microM; 24, 48, and 72 h) caused a decrease in cell viability in a concentration- and time-dependent way. This effect was still evident in cardiomyocytes exposed to YTX for 1, 5, and 24 h and cultured up to 72 h in YTX-free medium. Our results demonstrate that, at nanomolar concentrations, a short incubation with YTX causes an inhibition of the beating activity and an irreversible reduction of viability of cardiac cells in vitro.
authors.affiliation: Department of Materials and Natural Resources, University of Trieste, 34127 Trieste, Italy.
authors.forename: Valeria
authors.initials: V
authors.lastname: Dell'Ovo
authors.forename: Elena
authors.initials: E
authors.lastname: Bandi
authors.forename: Tamara
authors.initials: T
authors.lastname: Coslovich
authors.forename: Chiara
authors.initials: C
authors.lastname: Florio
authors.forename: Marina
authors.initials: M
authors.lastname: Sciancalepore
authors.forename: Giuliana
authors.initials: G
authors.lastname: Decorti
authors.forename: Silvio
authors.initials: S
authors.lastname: Sosa
authors.forename: Paola
authors.initials: P
authors.lastname: Lorenzon
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yasumoto
authors.forename: Aurelia
authors.initials: A
authors.lastname: Tubaro
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D006321:Heart / Q000187:drug effects*; D066298:In Vitro Techniques; D008978:Mollusk Venoms; D009206:Myocardium / Q000166:cytology* / Q000378:metabolism; D035964:Oxocins / Q000633:toxicity*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D008978:Mollusk Venoms; D035964:Oxocins; D000242:Cyclic AMP; C066632:yessotoxin; D002118:Calcium