The Effects of External K⁺ and Na⁺ on the Chemotaxis of Rabbit Peritoneal Neutrophils^1,2 Free

Extracellular K⁺ enhances the chemotactic responsiveness and spontaneous movement of rabbit peritoneal neutrophils but is not required for these functions. Other monovalent cations act the same; the rank order of their effectiveness is K⁺ = NH₄ τ; Rb⁺ Cs⁺ τ; Li = Na. The K⁺ specific ionophore, valinomycin (10^-7 M) inhances chemotaxis in the presence of K⁺ but not in its absence; another K⁺-specific ionophore, nigericin (10^-7 M) inhibits chemotaxis in the absence of K⁺ but not in its presence. Ouabain (5 × 10^-6 M) prevents the enhancing effects of K⁺ on chemotaxis. Removing the Na⁺ of the buffer and substituting it with K⁺, choline or glucose greately enhances spontaneous motility but depresses chemotactic activity. One hypothesis suggested by the above results is that as a part of their action, chemotactic factors stimulate a net influx of K⁺ into the neutrophil; and alternative or additional hypothesis is that chemotactic factors stimulate a net efflux of Na⁺ from the neutrophil.