Effect of chinoform on the function of biological membranes.

To investigate the mechanism by which the toxic effect of chinoform (5-chloro-7-iodo-8-quinolinol) develops, its action on the function of biological membranes was examined. Findings were: 1. Chinoform induced K+ release from red cells. This effect was increased by prior addition of Mg2+ and decreased by albumin, ruthenium red, or lanthanum chloride. 2. Chinoform induced K+ release from isolated rat liver mitochondria more effectively in the presence of Mg2+ or other bivalent cations, and a chinoform-Mg chelate was more effective than chinoform alone. The K+ release from mitochondria was protected by albumin and to a certain extent by lanthanum chloride. 3. The change in the ion permeability of mitochondrial membrane induced by chinoform in the presence of Mg2+ was accompanied by uncoupling of the oxidative phosphorylation. These results suggest that chinoform interacts with membranes more effectively as a metal chelate, producing conformational and functional changes in those membranes.