Epileptogenic effects of radiographic contrast agents: experimental study.

Electrical activity in cells directly exposed to water-soluble radiographic contrast agents was investigated by intracellular recordings from neurons of the abdominal ganglia of Aplysia. Measurements of membrane resting potential, membrane conductance, synaptic and action potential configuration, and spontaneous electrical activity were performed. Test solutions included sodium diatrizoate, meglumine iothalamate, metrizamide, and control solutions. Solutions (100 and 200 mOsm) of these agents did not significantly alter resting membrane potential, membrane conductance, action potential frequency or configuration, or excitatory postsynaptic potentials. Inhibitory postsynaptic potentials were suppressed by contrast agents. These results suggest that contrast agents affect at least some neurons by disinhibition.