Glucose-containing organ preservation solutions and intracellular acidosis.

We read with interest the excellent review by Belzer and Southard (1) on the principles of organ preservation by cold storage following vascular flushing. The UW solution developed by the authors holds the promise that improved preservation will be achieved, especially for organs other than the kidney, both in duration of safe storage and in quality of function in the early postreimpiantation phase. One concept that we would like to question. however. is the view that glucose present in the preservation solution (as in EuroCollins') can contribute to the developing acidosis during hypothermia. particularly in the liver. We have been undertaking l1p NMR spectroscopy studies on the response of liver to vascular flush and cold storage. using the conventional hypertonic citrate solution (which contains no glucose) and Collins' solution (a phosphate-based solution with high glucose content) (2,3). Using the chemical shift of the inorganic phosphate signal. we have followed the pH changes in the livers with time at hypothermia. In these experimental studies on the rat it is apparent that the pH fall in both solutions is identical (reaching by 8 hr pH 6.85±0.04 in citrate-flushed organs. and 6.86±O.03 in Collins' -flushed or· gans). Factors other than lactate accumulation can influence intracellular pH. including the hydrolysis of ATP, which liberates protons (5)-and from our studies we have no reason to implicate glucose contained in the storage solution as a major contributing factor in the hepatic acidosis. Indeed, in other studies (to be reported) when we used a phosphate-based preservation solution in which the glucose was completely replaced by mannitol, the intrahepatic pH fall was again identical to that seen in the glucose-containing medium. The metabolic pathways in play during hypothermia of mammalian cells still remain largely to be identified, and the interesting combinations of solutes in the solution developed by Belzer and Southard open up exciting new possibilities for organ preservation.