Perfused lung preparation for studying altered gaseous environments.

An isolated perfused lung (IPL) preparation was used to investigate the influence of acute environmental stress on lung substrate metabolism. The IPL apparatus consists of four perfusion flasks housed in a temperature-controlled Lucite box with a circulation fan. Lungs are ventilated by a positive pressure ventilation pump. The ventilation is arranged so that the lung can be ventilated with any desired gas composition with concomitant collection of expired gases. The perfusion medium is circulated at 10 ml/min with a peristaltic blood pump, and passes through a specially designed chamber to dampen pulmonary pressure and remove emboli. The perfusion medium presently used in our experiments consisted of washed bovine red blood cells resuspended to a 15% hematocrit with Krebs-Henseleit bicarbonate buffer containing 6% dialyzed Pentex bovine serum albumin. Circulating substrates include 6muM glucose and 0.4muM palmitate. The pH is adjusted to 7.4 with 0.8M Na carbonate. Lungs perfused for 1.5 hr with this apparatus maintain viability, show little edema, maintain blood gases, and show linear incorporation of labeled glucose into lung lipids. Perfused lungs made hypocapnic show a significant (p less than 0.05) rise in lactate and pyruvate, while perfused lungs made hypercapnia show a significant decrease in pyruvate with no change in lactate.