Cytotoxic and non-cytotoxic effects of the MEIC reference chemicals on spontaneously contracting primary cultured rat skeletal muscle cells

Abstract

This study was designed to evaluate the suitability of a multi-endpoint test system using primary cultured spontaneously contracting rat skeletal muscle cells to indicate an acute neuro- and/or cardiotoxic potential of chemicals. The concentration-dependent effects of the 50 MEIC (Multicenter Evaluation of In Vitro Cytotoxicity) reference chemicals on contractility, indicative of the functional integrity of the electrically active muscle cell membrane, were determined. Additionally, effects on two other endpoints, glucose consumption and viability, were monitored to reveal whether alterations in contractility were associated with cytotoxicity. In total, 30 of the tested compounds inhibited contractility at non-cytotoxic concentrations. The contractility-inhibiting and cytotoxic potencies differed by factors of more than 10 in the case of diazepam, phenol, propranolol, phenobarbital, mercuric chloride, thioridazine, verapamil, chloroquine, quinidine, phenytoin and atropine, of more than 100 in the case of amitriptyline, dextropropoxyphene, orphenadrine and amphetamine, and even more than 1000 for nicotine. On the basis of the available knowledge of the acute toxic effects and modes of acute toxic action of the test compounds, this characteristic response pattern is shown to be highly predictive for compounds reported to be cardio- and/or neurotoxic owing to interference with excitable membrane functions and/or neurotransmission.