Blog
About

11
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: not found

      [K+] dependence of polyamine-induced rectification in inward rectifier potassium channels (IRK1, Kir2.1)

      The Journal of General Physiology

      The Rockefeller University Press

      Read this article at

      ScienceOpenPMC
      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          The effects of permeant (K+) ions on polyamine (PA)-induced rectification of cloned strong inwardly rectifying channels (IRK1, Kir2.1) expressed in Xenopus oocytes were examined using patch-clamp techniques. The kinetics of PA-induced rectification depend strongly on external, but not internal, K+ concentration. Increasing external [K+] speeds up "activation" kinetics and shifts rectification to more positive membrane potentials. The shift of rectification is directly proportional to the shift in the K+ reversal potential (EK) with slope factors +0.62, +0.81, and +0.91 for 1 mM putrescine (Put), 100 microM spermidine and 20 microM spermine (Spm), respectively. The time constant of current activation, resulting from unblock of Spm, also shifts directly in proportion to EK with slope factor +1.1. Increasing internal [K+] slows down activation kinetics and has a much weaker relieving effect on block by PA: Spm-induced rectification and time constant of activation (Spm unblock) shift directly in proportion to the corresponding change in EK with slope factors -0.15 and +0.31, respectively, for 20 microM Spm. The speed up of activation kinetics caused by increase of external [K+] cannot be reversed by equal increase of internal [K+]. The data are consistent with the hypothesis that the conduction pathway of strong inward rectifiers is a long and narrow pore with multiple binding sites for PA and K+.

          Related collections

          Author and article information

          Journal
          J Gen Physiol
          The Journal of General Physiology
          The Rockefeller University Press
          0022-1295
          1540-7748
          1 August 1996
          : 108
          : 2
          : 105-113
          Article
          97007065
          2229312
          8854340
          Categories
          Articles

          Anatomy & Physiology

          Comments

          Comment on this article