24-hour preservation of isolated rat hearts perfused with pyridoxalated hemoglobin polyoxyethylene conjugate (PHP) solution at low temperature.

We examined the effects of long-term perfusion with pyridoxalated hemoglobin polyoxyethylene conjugate (PHP) solution on cardiac function of isolated rat hearts. Hearts were perfused with oxygenated Krebs-Henseleit (K-H) solution containing 3% PHP or hydroxyethyl starch (HES) at a constant pressure of 13 mm Hg for 24 h at 15 degrees C. After 24 h preservation, hearts were rewarmed with K-H solution. Heart rate (HR) in PHP-preserved hearts was almost the same as control and cardiac contractility was maintained at 70% of control, but coronary outflow decreased to about 50% of control. No edema developed in the PHP group. Addition of a Ca2+ antagonist, diltiazem, inhibited the elevation of the end-diastolic pressure significantly. In HES-preserved hearts, HR did not recover to control levels, but there was no significant difference in cardiac contractility between PHP- and HES-perfused hearts. The results demonstrate that isolated hearts can be preserved by perfusion with PHP solution under hypothermic conditions for 24 h and suggest that PHP solution would be useful for a perfusate of isolated organs and tissues for preservation.