Adenosine and amrinone reverse felypressin-induced depression of myocardial tissue oxygen tension in dogs

Abstract

Purpose: To determine whether continuous infusion of adenosine triphosphate (ATP), nitroglycerin (NTG) or amrinone (AM) would ameliorate the reductions in coronary blood flow (CBF) and myocardial oxygen tension (PmO2) induced by felypressin. Methods: Seven open-chest dogs were studied under urethane and alpha-chloralose anesthesia. Hemodynamic variables including heart rate (HR), systolic blood pressure, diastolic blood pressure (DBP), mean pulmonary artery pressure, pulmonary capillary wedge pressure, CBF (ultrasound flowmetry), PmO2 (polarography) and cardiac output (thermodilution method) were recorded. Felypressin was infused in a loading dose of 6 mlU·kg-1 for five minutes and then continued at 0.2 mlU·kg-1·min-1. After 30 min felypressin infusion, each agent was administered for 15 min to evaluate hemodynamic changes. Infusions were 100 and 200 μg·kg-1·min-1 for ATP, 2.5 and 5 μg·kg-1·min-1 for NTG, and 10 and 20 μg·kg-1·min-1 for AM. Results: After felypressin DBP increased by 17 ± 5 (mean ± SD)%; CBF decreased by 49 ± 9%; Cl decreased by 40 ± 13%; HR decreased by 29 ± 11%; PmO2 in the inner layer decreased by 21 ± 7%. The Cl and CBF returned to baseline after ATP 100 and 200 μg·kg-1·min-1, AM 10 and 20 μg·kg-1·min-1, but not after NTG. The PmO2 in the inner layer returned to the baseline value by any infusion except for NTG 5 μg·kg-1·min-1. Conclusion: Adenosine and amrinone, but not nitroglycerin reverse the adverse cardiovascular effects of felypressin.