Chloride and potassium movements from frog's sartorius muscle in the presence of aromatic anions

Summary The efflux of³⁶Cl and⁴²K from frog's sartorius muscles equilibrated in Ringer's fluid with added KCl were measured in the absence and presence of salicylate, benzoate, and acetylsalicylate. The transmembrane potential and resistance were also measured in sartorii under similar conditions. Although the rate coefficient for loss of⁴²K remained reasonably constant over extended experimental periods for untreated muscles, the rate coefficient for loss of³⁶Cl fluctuated in many muscles giving rise to minima and maxima. The aromatic anions mentioned increased the efflux of chloride while having no detectable effect on the potassium efflux. The aromatic anion-stimulated chloride efflux was insensitive to alterations of external pH and was markedly reduced when nitrate replaced external chloride. No detectable changes in transmembrane potential or resistance were produced by salicylate, the most extensively studied aromatic anion. The results suggest that salicylate and the other aromatic anions stimulate an exchange diffusion mechanism for chloride.