Electrophysiological effects of contrast media.

The effect of two low osmolar contrast media (sodium ioxitalamate and sodium ioxaglate) and two nonionic media (iohexol and iopamidol) on cellular electrophysiological properties of sheep myocardium and Purkinje fibres was studied at two concentrations of each medium. Neither sodium ioxitalamate nor ioxaglate had significant effects on any of the parameters measured. Iohexol (10 mL/L) caused a loss of resting potential, a decrease in action potential and duration, and a decrease in refractory period of the myocardium. No change in Purkinje fibres was observed. Iopamidol induced an increase in relative refractory period in both myocardium and Purkinje fibres at 1 mL/L and had a significant effect on all parameters studied at 10 mL/L. Automaticity was not observed after perfusion with any agent at either concentration.