Nitrogen monoxide and functional activity of large conductance Ca-activated potassium channels in coronary vessels in rats with limited motor activity
Solodkov, A.P.; Maĭorova, S.S.; Lazuko, S.S.
Rossiiskii Fiziologicheskii Zhurnal Imeni I.M. Sechenova 95(7): 736-749
2009
ISSN/ISBN: 0869-8139 PMID: 19803460 Document Number: 635231
The study was aimed at the detection of endothelial factors contribution and nitric monoxide produced by constitutional and inducible NO-synthase in regulation of Ca-activated potassium channels activity of high conductivity in immobilization stress. The experiments were conducted in isolated rat-female hearts after retrograde perfusion with Krebs-Henseleit solution bubbled with 95% O2, 5% CO2 at 37 degrees C. To study BK(Ca)-channels role in the regulation of coronary vessels tone and contractile myocardial function BK(Ca)-channel blocker tetraethylammonium (ImM/l concentration) (Sigma, USA) was added in perfused solution. The obtained results justify: firstly, the non-selective blockade of constitutional and inducible NO-synthase L-NAME accompanied by the reduction of coronary flow volume velocity to control values level in the group of animals underwent to stress; second, selective blocker of inducible NO-synthase S-methylisotiourea completely eliminates evoked by stress hypotonia of cardiac vessels and reduction of contractile activity of left ventricle in stressed rats; thirdly, stress reduces the functional activity of Ca-activated potassium channels and the removal of endothelium or blockade of nitric monoxide completely it restores.