Failure of epinephrine to induce severe cardiac arrhythmia in rats with ventricular hypertrophy secondary to aortic pressure overload.
The arrhythmogenic action of epinephrine was studied in 3 groups of rats: 10 rats with mild constriction of the abdominal aorta (group H1), 10 rats with severe constriction (group H2), 10 sham-operated age-matched rats (group C). Blood pressure and ECG were recorded before, during and after 5 min. perfusion of increasing doses of epinephrine (1, 5, 10 and 25 micrograms.kg-1.min.-1). Ventricular arrhythmia was evaluated from the ECG using a modified Lown's grading system. The ventricular hypertrophy index was calculated from the heart/body weight ratio (mg/g). The mean arterial blood pressure was significantly higher in groups H1 and H2 than in the control group. The ventricular hypertrophy was significant in group H2, but not in group H1. There was no significant difference between the amplitudes of the epinephrine-induced hypertensive responses in the 3 groups but the extent of arrhythmia was significantly lower in the animals with high hypertrophy index.
Lessard
Y
Y
Laboratory of Medical Physiology, Faculty of Medicine, Rennes, France.
Mabo
P
P
Daubert
J C
JC
Kerbaol
M
M
D000818:Animals; D001011:Aorta; D001145:Arrhythmias, Cardiac / Q000139:chemically induced* / Q000209:etiology; D001794:Blood Pressure; D006332:Cardiomegaly / Q000209:etiology / Q000503:physiopathology*; D003250:Constriction; D004837:Epinephrine / Q000633:toxicity*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains
D004837:Epinephrine