INTERSTITIAL ACCUMULATION OF NA-OUT AND COLD-STORAGE OF RAT LIVERS - IMPLICATIONS FOR GRAFT-SURVIVAL( AND K+ DURING FLUSH)

Intracellular-type electrolyte solutions were introduced into organ pr eservation to prevent K+ efflux and Na+ and Cl- influx into cells and cell swelling during cold ischemia. We studied cation accumulation in the interstitial space by microdialysis, during rat liver cold storage and after flush-out with high-K+ and low-K+ solutions. The effect of Na+ and K+ on graft function and survival was studied in an isolated p erfused liver model and an orthotopic transplantation model after rat liver storage in iso-osmolar high-K+ and low-K+ solutions. After 24 ho urs of cold ischemia [Na+](o) dropped from 136 +/- 2 mmol/L to 91.8 +/ - 1.1 mmol/L, and [K+](o) increased from 5.9 +/- 0.1 mmol/L to 12.2 +/ - 1.6 mmol/L (P < .001 vs, control). [Na+,](o) and [K+](o) after flush -out did not equilibrate with [Na+](sol) and [K+](sol) after 24 hours of cold storage, Rat livers preserved in low-K+ solutions produced sig nificantly more bile during isolated reperfusion and released less ala nine transaminase, aspartate transaminase, and lactate dehydrogenase i nto the reperfusion medium than high-K+ solutions. Rat liver survival after 14 hours of preservation was higher in low-K+ solutions (13 of 1 3) than in high-K+ solutions (7 of 13), Those studies indicate that du ring cold storage of rat livers, transmembraneous Na+-K+ sodium-potass ium exchange might not follow the 3:2 stochiometry of a sole sodium-po tassium exchange via Na+-K+ sodium-potassium adenosine triphosphatase (ATPase), and that low-K+ solutions might improve graft function and s urvival after rat liver preservation.