Control of canine kidney cortex slice volume and ion distribution at hypothermia by impermeable anions

Hypothermia induces swelling of dog kidney cortex slices. Swelling of cells during hypothermia is related to a number of factors including the permeability of Cl⁻. By substituting lactobionate for Cl⁻, while maintaining isoosmotic conditions, swelling is prevented. Lactobionate is an impermeable anion and its presence in the suspending fluid prevents swelling of dog kidney cortex slices in salts of Na⁺, K⁺ or combinations of Na⁺ and K⁺ even in the presence of metabolic inhibitors. By maintaining a ratio of 80 mM lactobionate: 60 mM chloride and an appropriate ratio of Na⁺:K⁺ (80 mM:60 mM), both the total tissue H₂O and ratio of intracellular K⁺/Na⁺ are kept within normal ranges during hypothermic incubation of tissue slices. Kidney cortex slices suspended in this medium at 30 °C respire at a rate 30–40% slower than that of control slices suspended in saline. A similar result is obtained by adding ouabain to slices suspended in saline. This suggests that the Na⁺-pump activity is suppressed under these conditions and results in a reduced energy demand on the cell. These results are discussed in relation to utilizing this type of solution for long-term perfusion preservation of kidneys for transplantation.