The isotherm for glucose absorption by aged potato (Solanum tuberosum var. Russet Burbank) discs shows four distinct phases in the concentration ranges 1.0 to 75 /AM, 75 gM to 1.

The effect of perfusate composition on duration of lung perfusion until development of alveolar edema was evaluated in isolated ventilated rat lungs perfused at a rate of 25 ml/min in a recirculating system. When the perfusate was Krebs-Ringer bicarbonate solution (KRB) alone, alveolar edema developed in 40-85 min. Addition of glucose (5 mM) slightly prolonged the time to edema while addition of 3% fatty acid-poor bovine serum albumin (BSA) extended mean survival to 3.5 hr. With KRB containing both glucose and BSA, mean survival was greater than 4 hr and three of eight lungs had not become edematous when the experiments were terminated at 5 hr. Similar results were obtained when a synthetic plasma-stimulating solution (SPSS) that is essentially free of protein or other colloid was used as a perfusate. Perfusion at reduced flow rates (12 ml/min) with KRB plus glucose and BSA or with SPSS gave 5-hr survival rates of 100%. These results indicate that prolonged lung perfusion is possible with a colloid-free artificial medium and suggest that both mechanical and metabolic factors are important in maintaining isolated perfused rat lungs free of alveolar edema.

The combination of a defined medium with single-pass perfusion has made possible long-term maintenance of beating rat hearts at 22 degrees C in vitro. The 6- to 9-day survival period appears to be the longest so far reported for hearts. This method provides a stable system which should be useful for investigating the role of single factors in myocardial preservation and evaluating the effects of exposure to pharmacological and toxicological agents.