Cardiac toxicities of antibiotics.

Isolated heart muscle preparations are useful in the study of cardiac toxicities of drugs and environmental chemicals: such tissues allow assessment of chemical effects on heart muscle that is free from indirect in vivo influences that can mask or even accentuate cardiac responses measured in the intact animal. In the present study, left atria of guinea pigs were used to demonstrate a direct cardiac depressant effect of greater-than-therapeutic concentrations of several aminoglycoside antibiotics. The toxic effect of these antibiotics seems to be a calcium-dependent event, and may prove useful to characterize contractile responses of the heart. Other antibiotic agents can also depress cardiovascular function, as summarized in this report, but mechanisms of action have not been clearly defined.