Effects of dilevalol in the anesthetized pig with a partially occluded coronary artery

The beta-adrenoceptor antagonist dilevalol in a total dose of 430 micrograms/kg i.v., potently suppressed isoprenaline-induced increases in heart rate and max LVdP/dt (dose ratios of 42 +/- 6 and 38 +/- 5, respectively, in anesthetized pigs), but a dose of 1430 micrograms/kg did not appreciably modify phenylephrine-induced increases in arterial blood pressure (dose ratio less than 4) in both anesthetized and conscious pigs. The actions of dilevalol on ischemic myocardium of anesthetized pigs were investigated following a reduction of left anterior descending artery flow by 85-90%. Dilevalol (300 micrograms/kg), administered after 15 minutes of ischemia, did not affect the ischemia-induced changes in systemic hemodynamics (such as heart rate, max LVdP/dt and cardiac output), myocardial perfusion, and wall-thickening of the ischemic segment during the following 15 minutes of ischemia and 2 hours of reperfusion. The reasons for the lack of antiischemic actions are most likely the absence of negative chronotropy and an absence of afterload reduction by dilevalol.