[Amrinone (50 micrograms.kg-1.min-1) does not impair regional myocardial tissue metabolism during the 40%-decrease of...

We investigated the effects of amrinone on metabolism of regional myocardial tissue during the 40%-decrease of left anterior descending coronary (LAD) flow in anesthetized dogs. Fourteen adult mongrel dogs weighing 15.4 +/- 5.1 kg were anesthetized with 0.5% isoflurane in 50% oxygen and ventilated mechanically to maintain normocapnia. After thoracotomy, regional myocardial tissue PO2 was measured using a monopolar polarographic needle electrode inserted in the myocardium. Electromagnetic blood flow probes were placed around LAD and circumflex artery. A 23-gauge catheter was inserted into a coronary vein which runs along LAD to obtain coronary venous blood for measuring oxygen content, lactate and pyruvate. A variable constrictor was placed distal to the flow-probe. After decreasing LAD flow for 40%, cardiac index (CI) decreased. Systemic venous resistance was decreased and CI was increased by amrinone (50 micrograms.kg-1.min-1) infusion. Myocardial tissue oxygen tension, venous lactate, lactate extraction, lactate-pyruvate ratio and excess lactate were all unchanged by amrinone. In conclusion, amrinone does not impair myocardial aerobic metabolism and increases CI under the stenosis of coronary artery.