EFFECTS OF EPINEPHRINE AND NOREPINEPHRINE ON HEMODYNAMIC PARAMETERS AND ARRHYTHMIAS DURING A CONTINUOUS-INFUSION OF AMITRIPTYLINE IN RATS

Epinephrine and norepinephrine were evaluated in treatment of hemodyna mic compromise in amitriptyline intoxication. One hundred and one male Wistar rats were monitored hemodynamically during amitriptyline intox ication and given one of three infusion rates (0.1, 0.5 or 5.0 mg/kg/m in) of either epinephrine or norepinephrine. Sixteen rats served as co ntrols and received only glucose after intoxication. Amitriptyline int oxication lowered mean arterial pressure, heart rate, left ventricular max dP/dt, and increased left ventricular end-diastolic pressure. All doses of norepinephrine and the two higher doses of epinephrine incre ased mean arterial blood pressure and left ventricular max dP/dt. Hear t rate increased with both drugs, more with epinephrine, but not beyon d pre-intoxicated levels at any dose. Left ventricular end-diastolic p ressure was unaltered by both drugs. Malignant arrhythmias appeared in 7% of all animals, whereas a progressive decline of cardiac contracti lity caused cardiac arrest in 36% of all animals. This suggests that m yocardial depression is the aspect most likely to cause death. At inte rmediate doses epinephrine resulted in significantly fewer arrhythmias and lower mortality compared to norepinephrine. We conclude that epin ephrine and norepinephrine each appeared effective in reversing amitri ptyline-induced hemodynamic alterations. Epinephrine had fewer arrythm ogenic properties than norepinephrine and may be preferable to norepin ephrine.