Experimental observations on the mode of action of “intracellular” flush solution

Experiments were conducted using rabbit kidneys stored on ice for 48 hr to elucidate the mode of action of “intracellular” flush solutions. Measurements were made of renal function on a shunt and they were correlated with blood flow and the efficiency of the mechanical expulsion of red cells. By comparison with unflushed, ice-stored kidneys, near complete mechanical expulsion of blood by 30 to 60 min of continuous perfusion with hypertonic Ringer's albumin resulted in significantly higher blood flow with little gain in function. Similarly, increasing the content of nonelectrolyte in Ringer's albumin improved blood flow but not function. A simple flush with a low ionic strength sodium solution (LIE), containing impermeant anions and glucose was superior to that with Ringer's albumin. A high-potassium version of the low ionic strength solution (LIC) was in turn significantly better than LIE for kidney preservation by simple flushing and ice storage. These results were interpreted to mean that whereas mechanical flushing is a relatively minor component of the action of flush solutions, the major benefit results from a reduced sodium and elevated potassium content in the presence of impermeant anions. The primary importance of prevention of cell swelling by the inclusion of nonelectrolytes in “extracellular” flush solutions, is questioned.