Selective accumulation of potassium ion by gel and kidney slices

• 1.

  1. Slices of denatured protein gels and cortical slices from the kidneys of adult rats were subjected to equivalent experimental conditions in order to determine the factors promoting selective K⁺ accumulation.

• 2.

  2. The addition of polythelene glycol 6000 to the medium decreased the water content of rat kidney cortex slices at 0° and at 38°, and was used to control swelling at low concentrations of ions.

• 3.

  3. K⁺ selectivity of slices of gel at 20° and of anaerobic tissue at 38° incubated in media of constant composition decreased as the water content increased.

• 4.

  4. K⁺ selectivity of slices of gel at 20° and of kidney cortex incubated both at 0° and anaerobically at 38° increased as the concentrations of Na⁺ and K⁺ in the medium were decreased whilst the Na⁺/K⁺ ratio and the water content of the slices were held constant.

• 5.

  5. K⁺ selectivity of slices of gel at 20° and of kidney cortex incubated anaerobically both at 38° and at 0° increased as the relative concentration of K⁺ in the medium decreased whilst the sum of the concentrations og Na⁺ and K⁺ in the medium and the water content of the slices were held constant.

• 6.

  6. These results have been interpreted in terms of a model first proposed for ion- exchange resins. It has been shown that with further assumptions the model could account for the asymmetric distribution of Na⁺ and K⁺ in respiring tissue, and for the swelling, uptake of Na⁺ and loss of K⁺ that occur with anoxia at 38° or on chilling to 0°.