Factors affecting the swelling of kidney cortex slices at o°

Abstract

Factors affecting swelling of slices of rabbit kidney cortex at o° in isotonic salines containing Na + as the main cation and Cl − as the bulk anion were examined. 1. 1. Tissue hydration and chlorides increase with increasing concentration of K + in the leaching medium. A similar swelling effect was shown for Rb +, but not for Li +. 2. 2. A linear relationship was shown to exist between the apparent membrane potential, calculated from the Donnan ratio of potassium, and the logarithm of the external potassium concentration. 3. 3. An inverse relationship was demonstrated between tissue water and the apparent Donnan ratios of chloride and potassium: as compared with controls leached at O° in standard saline ( [ Cl −] o [ Cl −] i = 1.495 ± 0.037; [ K +] i K +] o = 8.86 ± 0.35 ) factors increasing tissue swelling, e.g., 0.2−0.6 mM HgCl 2, 0.7−1.4 mM Esidrone, 2–149 mEqu K +, 67 and 134 mEqu Rb +, decreased [ Cl −] o [ Cl −] i and [ K +] i [ K +] o , whilst 1−6 m M Ca 2+, Ba 2+, Sr 2+ and Mn 2+ decreased tissue swelling and also increased these ratios. 4. 4. The relationships found between tissue water and the apparent Donnan ratios of chloride and potassium correspond to a derived relationship of the osmotic gradient and the ratio [ Cl −] o [ Cl −] i for a double Donnan system.