Effects of Two α-Adrenoceptor Antagonists, Nicergoline and Phentolamine, on Myocardial Oxygen Consumption in the Dog

We compared the effects of two α-adrenoceptor antagonists, nicergoline and phentolamine, on myocardial oxygen consumption (MVO2) in open-chest dogs. Intravenous nicergoline, 2 μg/kg/min for 30 min. reduced blood pressure from 130 ± 6 to 100 ± 2 mm Hg. did not change heart rate, and reduced MVO2/beat from 63.1 ± 6.6 to 43.6 ± 4.0 μl (p < 0.05, compared with control saline-infused and phentolamine-treated dogs). Intravenous phentolamine, 8 μg/kg/min, reduced blood pressure from 123 ± 6 to 95 ± 8 mm Hg and increased heart rate from 199 ± 4 to 235 ± 9 beats/min (p < 0.05, compared with control and nicergoline-treated dogs). MVO2/beat did not change, but MVO2 increased from 11.1 ± 1.5 to 13.1 ± 2.0 ml/min (p < 0.05, compared with nicergoline-treated dogs). These results suggest that nicergoline may be perferable to phentolamine in patients in whom it is important to avoid any increase in MVO2.