EFFECTS OF PERFUSION MEDIA ON THE Ca++ AND Mg++ CONTENT OF RAT LIVER

Abstract

Normal adult male rats were injected with 45CaCl2 intraperitoneally, and radioactivity in whole blood and liver was assayed at intervals of 10 minutes to 48 hours; the results showed rapid equilibration of 45Ca in the liver. In different animals, hepatic perfusion was carried out 4 hours after intraperitoneal injection of 45CaCl2. Portal perfusion with 100 ml of Krebs–Ringer phosphate (KRP) solution removed over 90% of the 45Ca from the liver, and addition of 0.5% EDTA to the solution did not alter the amount removed, although it resulted in earlier 45Ca washout. In other groups of rats, Ca++ and Mg++ concentrations were measured by atomic absorption spectrophotometry in samples of unperfused liver, and livers perfused with various media. Perfusion with KRP had little effect, but KRP + EDTA removed 60% of the Ca++ and 10% of the Mg++, whereas Ca++- and Mg++-free KRP removed 76% of the liver Ca++ but only 4% of the Mg++. It is concluded that tissue Ca++ is extremely loosely bound, and that EDTA effects on cell adhesion and permeability are due primarily to removal of tissue Ca++.