The effects of digoxin and dopamine on the oxygen consumption, lactate production and haemodynamic performance of an isolated, perfused, working guinea-pig heart
We have adapted an established technique for perfusing the isolated, working rat heart to the guinea-pig heart and characterized its biochemical and haemodynamic performance. After 20 min of anoxia the heart recovers about 50% of its pre-anoxic performance ('post-anoxic cardiac failure') and after 90 min of continuous work total cardiac output falls to 50% of its initial, stable value ('spontaneous cardiac failure'). We have studied the effects of digoxin (10-7M and 2 × 10-7M) and dopamine (10-5M) on these two forms of cardiac failure and shown that digoxin improves the haemodynamic performance of the heart without altering its metabolism and therefore increases its efficiency. In contrast dopamine improves the haemodynamic performance of the heart at the expense of increased aerobic and anaerobic metabolism. The preparation is of value in studying the effects of cardioactive drugs on hearts subjected to constant pre-load and after-load. © 1982.