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

Background: Clinically, intracellular type solutions are the most widely us ed solutions to preserve organs. The optimal ion composition of preservatio n solutions, however, is still unknown and extracellular-type solutions hav e frequently been superior to intracellular solutions in various experiment al studies. Materials and methods: In this study, we measured extracellular (interstitial) electrolyte concentrations in rat livers, kidneys, hearts a nd lungs at 4 degrees C by means of microdialysis sampling. Results: 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 live rs, 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 intracel lular-type solutions, [Na+](int) was significantly lower for each organ (ra nge from 69 +/- 8 mmol/l to 73 +/- 20 mmol/l) and [K+](int) was significant ly higher (range from 8.0 +/- 1.7 mmol/l to 9.8 +/- 1.0 mmol/l). In no inst ance did the interstitial electrolyte concentration equilibrate with the in tracellular 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). Conclusions: These studies indicate that during cold s torage of rat hearts, lungs, livers and kidneys, intra- and extracellular e lectrolytes do not equilibrate. Ion exchange stabilises at extracellular Na + concentrations between 87 mmol/l and 115 mmol/l and K+ concentrations bet ween 6.3 mmol/l and 6.9 mmol/l. Storage of organs in solutions with extrace llular-type ion compositions might improve graft function and survival not only after lung and liver but also after heart and renal preservation.