High- or low-potassium solutions for the storage of abdominal and thoracic organs

Clinically, intracellular type solutions are the most widely used solutions to preserve organs. The optimal ion composition of preservation solutions, however, is still unknown and extracellular-type solutions have frequently been superior to intracellular solutions in various experimental studies.

In this study, we measured extracellular (interstitial) electrolyte concentrations in rat livers, kidneys, hearts and lungs at 4 degrees C by means of microdialysis sampling.

After 24 h cold ischaemia, [Na+]int and [K+]int were 104 +/- 25 mmol/l and 6.5 +/- 0.7 mmol/l in hearts, 92 +/- 12 mmol/l and 6.9 +/- 1.0 mmol/l in livers, 115 +/- 22 mmol/l and 6.3 +/- 0.9 mmol/l in kidneys and 87 +/- 17 mmol/l and 6.4 +/- 0.6 mmol/l in lungs. After preservation of organs in intracellular-type solutions, [Na+]int was significantly lower for each organ (range from 69 +/- 8 mmol/l to 73 +/- 20 mmol/l) and [K+]int was significantly higher (range from 8.0 +/- 1.7 mmol/l to 9.8 +/- 1.0 mmol/l). In no instance did the interstitial electrolyte concentration equilibrate with the intracellular electrolyte concentration. When the diffusion gradient from the vascular space to the interstitial space was calculated for Na+ and K+, a significantly higher barrier was found for K+ than for Na+ (P<0.001 and P<0.01 for hearts).

These studies indicate that during cold storage of rat hearts, lungs, livers and kidneys, intra- and extracellular electrolytes do not equilibrate. Ion exchange stabilises at extracellular Na+ concentrations between 87 mmol/l and 115 mmol/l and K+ concentrations between 6.3 mmol/l and 6.9 mmol/l. Storage of organs in solutions with extracellular-type ion compositions might improve graft function and survival not only after lung and liver but also after heart and renal preservation.