[The cation specificity of the potassium and gramicidin channels of muscle fiber membrane].
Conductance ratios (Gi/Gk) and permeability ratios (Pi/Pk) for monovalent cations in frog muscle fibres have been defined under constant current conditions using a double sucrose gap method. Selectivity determined from potassium channel conductance is: K+ greater than Rb+ greater than Cs+ greater than greater than NH4+ greater than Na+ greater than Li+. In gramicidin channels both the permeability and conductance sequences are identical: NH4+ greater than Cs+ greater than Rb+ greater than K+ greater than Na+ greater than Li+. In isotonic K+-sulfate solution with one-sided addition of external [Tl+] (2.5 x 10(-3)-20 x 10(-3) M), differences in the conductance and permeability ratios for gramicidin channel were observed.
Shvinka
N E
NE
Caffier
G
G
D000818:Animals; D002412:Cations; D002463:Cell Membrane Permeability / Q000187:drug effects; D004553:Electric Conductivity; D006096:Gramicidin / Q000494:pharmacology*; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D008433:Mathematics; D008564:Membrane Potentials / Q000187:drug effects; D009132:Muscles / Q000187:drug effects / Q000502:physiology*; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D011893:Rana esculenta
D002412:Cations; D007473:Ion Channels; D015221:Potassium Channels; D006096:Gramicidin
Kationnaia spetsifichnost' kalievykh i gramitsidinovykh kanalov membrany myshechnogo volokna.