title: [Effect of thallium ions on gramicidin-induced conductance of muscle fiber membranes].
abstract: Conductance of single fibres from m. ileofibularis of Rana esculenta was studied in isotonic K2SO4 solution under constant current conditions using the double sucrose gap method. It was found that Tl+ (at concentrations 5, 10, and 20 mM) blocked K+ currents in the gramicidin channel. The decrease of K+ conductance caused by Tl+ was associated with the changes of the membrane potential. Both the decrease of K+ conductance and value of permeability ratio (PTl/PK) found from the membrane potential changes depended on Tl+ concentration in the bathing solution. No effect of Tl+ on the potassium channels was registered in the absence of gramicidin channels. The Tl+ block described here proves the existence of Tl+ ion binding within gramicidin channels of the muscle membrane and interactions among ions in the channels.
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000502:physiology; D002463:Cell Membrane Permeability / Q000187:drug effects; D004347:Drug Interactions; D006096:Gramicidin / Q000494:pharmacology*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D009132:Muscles / Q000502:physiology* / Q000648:ultrastructure; D011893:Rana esculenta; D013793:Thallium / Q000494:pharmacology*
chemical_list: D006096:Gramicidin; D013793:Thallium
vernacular_title: Deĭstvie ionov talliia na indutsirovannuiu gramitsidinom provodimost' membrany myshechnogo volokna.