The capacity of N-isopropyl-p-nitro-phenylethanolamine (INPEA) to influence the course of ouabain-induced cardiotoxicity in the cat

In previous reports we demonstrated a correlation between the capacity of drugs to depress the terminals of cat soleus nerves and their capacity to block ouabain-induced ventricular rhythm disorders. To test this correlation we examined the neurodepressant activity of INPEA, an agent which has been reported to be ineffective in antagonizing digitalis-induced arrhythmias. We found INPEA to have neurodepressant actions but that expression of these actions required more drug than had been used in previous studies of the drug's antiarrhythmic activity. When the neurodepressant doses were tested, they were found to be effective in antagonizing ouabain-induced ventricular tachycardia and death. The results are discussed with regard to the role of neural and myocardial depression in the control of digitalis-induced arrhythmias.