Robineau_1987_Toxicol.Lett_37_95

Cardiac toxicity of S-(2-diisopropylaminoethyl)-O-ethylmethyl phosphonothiolate (VX) has been investigated in the dog. Conscious or open-chest anaesthetized animals were subcutaneously injected with VX (1.5, 3.0 or 6.0 micrograms/kg b.w.). Blood cholinesterase activity decreased to 60%, 20% and 18% respectively of initial values. Only in the 6.0 micrograms/kg-treated group, heart rate, arterial and left intraventricular pressures and contractility index slightly but significantly decreased. In some dogs, treated with either 3.0 micrograms/kg or 6.0 micrograms/kg b.w. of VX, the electrocardiogram was changed: the Q-T interval was lengthened and arrhythmias (atrioventricular blocks, ventricular premature complexes. 'Torsade de pointe') were observed. Plasma non-esterified fatty acid concentrations were identical in control and VX-poisoned dogs. This study shows that, besides the expected cardiac effects resulting from muscarinic stimulation, VX can affect ventricular function through a yet unknown mechanism.