Faculty of Biology, University of Latvia
Hard copy: ISSN 1691–8088
On-line: ISSN 2255–9582
Acta Univ Latv (2007) 723: 21–26
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Environmental and

Acta Univ Latv (2007) 723: 21–26

Orginal Article

Investigation of ion selectivity in membranes of muscle cells

Nora Shvinka1,2*
1Institute of Anatomy and Antropology, Stradins University, Kronvalda Bulv. 9, Rīga LV-1010, Latvia
2Institute of Experimental and Clinical Medicine, University of Latvia, O. Vācieša 4, Rīga LV-1004, Latvia
*Corresponding author, E-mail: mbrazma@latnet.lv


The sequences of conductance ratios (GX/GK) and permeability ratios (PX/PK) for monovalent cations (X = Rb+, Cs+, Na+, Li+, NH4+) were studied in frog skeletal muscle before and after addition of the channel-forming antibiotic gramicidin A. The experiments were carried out under current clamp conditions using a double sucrose gap technique. For inwardly rectifying potassium channels the selectivity measured by membrane conductance ratios before gramicidin treatment was K+ > Rb+ > Cs+ > NH4+ > Na+ > Li+. In gramicidin channels of the same muscle fibre after addition of 5 × 10–7 M or 1 × 10–6 M gramicidin both the permeability and the conductance ratios had the sequence NH4+ > Cs+ > Rb+ > K+ > Na+ > Li+.

Key words: frog muscle fibre, gramicidin channel, inward rectifier potassium channel, ion conductance, ion selectivity, permeability.

Acta Univ Latv (2007) 723: 21–26
 DOI: http://doi.org/10.22364/eeb

Prof. Gederts Ievinsh
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University of Latvia

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