Effect of neuromuscular blocking agents pancuronium bromide and its monoquaternary analogue Org NC 45 on regional blood flow and cardiac metabolism in pigs

Abstract

AbstractThe effects of pancuronium bromide (60, 120, 300, and 600 μg.kg−1, i.v.) and its monoquaternary analogue Org NC 45 (300,750, and 1500 μg.kg−1, i.v.) on the systemic and regional hemodynamic variables were studied in the anesthetized pig. Pancuronium exhibited a dose‐dependent positive chronotropic and inotropic activity. The enhanced oxygen requirement of the myocardium was successfully met by a combination of higher blood supply to, and oxygen extraction by, the tissue. No changes were noticed in cerebral, renal or hepatic arterial blood flow. On the other hand, Org NC 45, which unlike pancuronium lacks vagolytic and sympathomimetic actions, did not cause an increase in heart rate or left ventricular dP/dtmax (LV dp/dtmax). Instead, in the two highest doses (750 and 1500 μg.kg−1) Org NC 45 decreased arterial blood pressure, LV dP/dtmax and the blood supply to the brain, kidneys, and liver. Neither compounds showed any effect on cardiac metabolism of glucose, lactate, or free fatty acids (FFA), although arterial blood glucose concentration did decrease following the two highest doses of each compound. Since Org NC 45, in a dose of 300 μg/kg−1, which is seven to ten times the ED90 for neuromuscular paralysis in man, is completely devoid of systemic and regional hemodynamic effects, and pancuronium in similar dose ratio is not, Org NC 45 might be preferred for use in cardiac anesthesia.