Effects of two alpha-adrenoceptor antagonists, nicergoline and phentolamine, on myocardial oxygen consumption in the dog.

We compared the effects of two alpha-adrenoceptor antagonists, nicergoline and phentolamine, on myocardial oxygen consumption (MVO2) in open-chest dogs. Intravenous nicergoline, 2 micrograms/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 microliters (p less than 0.05, compared with control saline-infused and phentolamine-treated dogs). Intravenous phentolamine, 8 micrograms/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 less than 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 less than 0.05, compared with nicergoline-treated dogs). These results suggest that nicergoline may be preferable to phentolamine in patients in whom it is important to avoid any increase in MVO2.