STORAGE OF RAT-LIVER FOR PLASMA-MEMBRANE ISOLATION

We described a procedure for the preservation of rat liver which makes possible the isolation of plasma membranes after 10 days storage at - 70 degrees C. The yield of plasma membranes obtained from the liver ti ssue kept at -70 degrees C for 10 days (3.43 +/- 0.08 mg protein/10 g wet liver) was not different statistically (P > 0.05) from the yield o f freshly obtained plasma membranes (3.32 +/- 0.05 mg protein/10 g wet liver). However, a significantly low yield (2.65 +/- 0.08; P < 0.01) was obtained from 90 days stored rat liver when compared with the imme diate isolation. Plasma membrane Na+, K+ ATPase and 5'nucleotidase act ivities of the stored liver for 10 days were not different statistical ly (P > 0.05) from the enzyme activities of the freshly isolated membr ane fractions. In contrast there was a significant decrease (p < 0.000 1) in the activities of both plasma membrane Na+, K+ ATPase and 5'nucl eotidase activities of 90 days stored rat liver at -70 degrees C when compared with immediate isolation. Considering the electron microscopi c findings; we observed that the preservation of the integrity of the plasma membrane fractions obtained from fresh and frozen livers for 10 and 90 days seemed to be parallel to the biochemical results. Therefo re we suggest that, storage of rat liver tissue for 10 days make feasi ble to maintain the experimental design and give convenience for obtai ning intact plasma membrane fractions.