Induction of failure in gas-perfused hearts by intermittent administration of Krebs solution. The effect of digitalis glycosides.

Our previous work has shown that kitten hearts perfused with a warm, moist mixture of 5% CO2-95S O2 beat strongly for many hours. We now show that after 1 hr of gas perfusion, intermittent administration of small volumes of Krebs solution (5 ml every 30 min to total of 20 ml) causes progressive failure of the heart. Washout cardiac failure is accompanied by loss of protein from the hearts. We have isolated a cardiotonic material from the washout liquid by precipitation with ammonium sulfate. This material is more active in failed than in normal isolated kitten atria. Preperfusion with digitalis glycosides (10to 10~ g/ml) protects hearts against failure and loss of protein during periods of washout with saline. ADDITIONAL