Cardioplegic solutions of the extracellular type are commonly used as storage media for heart transplants. Because this type of formulation was not originally designed for preventing hypothermically induced
edema, we assessed the effects of supplementing a standard, extracellular-like
cardioplegic solution with the high molecular weight impermeant
lactobionate on water content and postischemic compliance of isolated rat hearts. In one series of experiments, hearts were immersed in either a standard
cardioplegic solution of the extracellular type or in the same
solution supplemented with
lactobionate (80 mmol/L). Hearts were then processed for measurements of water content after 4 hours, 6 hours, and 8 hours of storage at 4 degrees C. In a second series of experiments, hearts were stored in the same solutions for 4 hours and 8 hours and subsequently reperfused for 1 hour on a Langendorff column, at which time left ventricular pressure-volume curves were constructed and compared with those obtained during the preischemic perfusion.
Lactobionate-treated hearts gained significantly less water than controls after 4 hours and 6 hours of storage, but the difference was no longer significant at the 8-hour time point. In contrast, the treated group yielded a significantly better recovery of compliance after both 4 hours and 8 hours of storage, suggesting that
lactobionate might exert protective effects in addition to those caused by its impermeant properties, possibly involving
calcium chelation and subsequent limitation of
calcium-dependent
contracture. Extracellular-type
cardioplegic solutions are attractive because a single
solution can be used during all phases of the
transplantation procedure.(ABSTRACT TRUNCATED AT 250 WORDS)