RESUMO
BACKGROUND: Organophosphorus, DDT, and pyrethroid insecticides are potent neurotoxic compounds. In addition, serious cardiovascular toxic manifestations such as ventricular arrhythmias have been reported. The objective of the present work was to study possible cardiac electrophysiologic effects of the type II pyrethroid, deltamethrin. METHODS: The effects of deltamethrin were studied in enzymatically isolated cat ventricular myocytes. Whole cell, patch-clamp technique was used in current- and voltage-clamp modes. RESULTS: Deltamethrin significantly increased action potential duration. Under voltage-clamp conditions, the most striking effects of deltamethrin were on sodium current. Pyrethroid induced a sustained component of the sodium current and caused a negative shift in current-voltage relation for peak current. The drug also slightly inhibited delayed rectifying outward potassium current. CONCLUSIONS: Pyrethroid type II, deltamethrin, increased action potential duration due to modulation of sodium current. This effect of deltamethrin can be potentially arrhythmogenic because it can induce Q-T prolongation of ECG and ventricular arrhythmias of the torsade-de-pointes type.