Journal archive > 2011 > N 5 September-October

THE HETEROGENEITY OF THE Na+,K+-ATPase OUABAIN SENSITIVITY IN MICROSOMAL MEMBRANES OF RAT COLON SMOOTH MUSCLES

A. A. Kaplia

Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
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The dose dependence of the Na+,K+-АТРase ouabain inhibition in the rat colon smooth muscle permeabilized microsomes has been analyzed according to the model of two independent binding­ sites of inhibitor to determine the activity of separate molecular forms of the enzyme that differ by affinity for cardiac glycosides. The two-phase inhibition curve with moderate content of the high-affinity activity component was revealed. The apparent inhibition constant of the low-affini­ty component corresponds to the value for the rat kidney microsomal Na+,K+-АТРase (?1-isoform). The specific role of the ?2- and ?1- Na+,K+-АТРase catalytic subunit isoforms in colonic smooth muscle electromechanical coupling is considered.

Key words: Na+,K+-АТРase, isoforms, ouabain, smooth muscle, colon.

The original article in Russian is available for download in PDF format.

© The Ukrainian Biochemical Journal