1. (chemistry) a radical cation of potassium with a charge number of 1
    • 1988 April 1, Miller, Christopher; Stahl, Neil; Barrol, Margaret, “A thermodynamic analysis of monovalent cation permeation through a K⁺-selective ion channel”, in Neuron[1] (in English), page 159:
      For Li⁺, Na⁺, K⁺, and Rb⁺, the enthalpy of binding to the channel is close to zero.
    • 2008 June 1, Daniels, David, “Ion Channels Play Key Role in R&D”, in Genetic Engineering & Biotechnology News[2], volume 28, number 11 (in English), ISSN 1935-472X, OCLC 77706455, archived from the original on 2010-01-02, page 24:
      Ion channels, which facilitate this movement, are protein assemblies that penetrate the membrane and catalyze passage of specific ions such as sodium (Na+), potassium (K+), or calcium (Ca2+) into or out of the cell down the electrochemical gradient.