title: Altered cytosolic Ca2+ dynamics in cultured Guinea pig cardiomyocytes as an in vitro model to identify potential cardiotoxicants.
abstract: Altered intracellular calcium (Ca(i)(2+)) handling by cardiomyocytes has been implicated in drug-induced cardiomyopathy and arrhythmogenesis. To explore whether such alterations predict cardiotoxicity, Ca(i)(2+) imaging was conducted in cultured, spontaneously contracting Guinea pig cardiomyocytes to characterize the effects of 13 cardiotoxicants and 2 safe drugs. All cardiotoxicants perturbed Ca(i)(2+) at therapeutically relevant concentrations. The cytotoxic chemotherapeutics doxorubicin and epirubicin, known to cause cardiomyopathy, preferentially reduced Ca(i)(2+) transient amplitude and sarcoplasmic reticulum (SR) Ca(2+) content, whereas Torsade de Pointes (TdP) inducers and potent hERG channel blockers (amiodarone, cisapride, dofetilide, E-4031 and terfenadine) predominately suppressed diastolic Ca(i)(2+) and contraction rate, and prolonged Ca(i)(2+) transient duration. The molecularly targeted cancer therapeutics, sunitinib and imatinib, exhibited profound effects on Ca(i)(2+), combining effects of cytotoxic chemotherapeutics, TdP inducers and potent hERG channel blockers. TdP inducers lacking direct hERG inhibition, ouabain and pentamidine, significantly elevated Ca(i)(2+) transient amplitude and SR Ca(2+) content while aconitine primarily accelerated automaticity and elevated diastolic Ca(i)(2+) similar to ouabain. Finally, amoxicillin and aspirin did not exert any significant effects on Ca(i)(2+) at concentrations up to 100 microM. These results suggest that detecting altered Ca(i)(2+) handling in cultured cardiomyocytes may be used as an in vitro model for early cardiac drug safety assessment.
authors.affiliation: Safety Pharmacology, Department of Toxicology and Pathology, Non-Clinical Safety, Hoffmann-La Roche, Inc, Nutley, NJ 07110, USA.
authors.forename: Jian-Yong
authors.initials: JY
authors.lastname: Qian
authors.forename: Liang
authors.initials: L
authors.lastname: Guo
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000633:toxicity; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects*; D002478:Cells, Cultured; D003600:Cytosol / Q000187:drug effects* / Q000378:metabolism*; D003627:Data Interpretation, Statistical; D004305:Dose-Response Relationship, Drug; D005456:Fluorescent Dyes; D016257:Fura-2; D006168:Guinea Pigs; D006331:Heart Diseases / Q000139:chemically induced* / Q000473:pathology; D007473:Ion Channels / Q000187:drug effects; D009200:Myocardial Contraction / Q000187:drug effects; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism; D016171:Torsades de Pointes / Q000139:chemically induced / Q000473:pathology
chemical_list: D000970:Antineoplastic Agents; D005456:Fluorescent Dyes; D007473:Ion Channels; D002118:Calcium; D016257:Fura-2