[Participation of ATP-sensitive potassium channel in autoregulation of coronary blood flow under the condition of limited motor activity].
The aim of study involved detection of the effect of the K(ATP)-channel blocker glibenclamide on autoregulation of coronary flow, the expression of reactive hyperemia, the value of coronary dilatation reserve, and the myocardial contractile function in isolated rat hearts after a 6-hour immobilization stress. The experiments have been performed on 64 isolated rat hearts (female): into the cavity of left ventricle, a latex balloon connected with electromanometer has been introduced. Every experiment consisted of 2 stages. The heart has been perfused by Krebs-Henseleite solution in the first stage, and in the second stage--by the same solution with glibenclamide (1 mkM) or its combination with verapamile (10(-)6 M) or saponin (44 mcg/ml of coronary flow within 2 minutes) added to it. During the experiment, the perfusion pressure has been elevated step by step from 40 to 120 mm Hg with 20 mm Hg steps (coronary autoregulation). In rats after immobilization, the glibenclamide effect on cardiac vessel tone and expression of maximal hyperemic coronary flow (in contrast to its influence on myocardial contractile function) is lower than in control and depends on endotheliocyte presence which suggests an important role of endothelium in maintaining cardiac vessel smooth cell activity of K(ATP)-channels inhibited under the stress condition. After immobilization stress, the role of endothelium in the reactive hyperemia origin was enhanced, that of the K(ATP)-channels was reduced. The general activity of both mechanisms of tone regulation of cardiac vessels remains the same as in control. This suggests that the K(ATP)-channels as nitric monoxide and eicozanoids are the local system of myogenic tone regulation of the rat cardiac vessels; that the rat immobilization inhibits the activity KATp-channel's smooth cells of coronary vessels and creates a marked dependence of their activity on endothelium presence.
Solodkov
A P
AP
Lazuko
S S
SS
D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology*; D003326:Coronary Circulation / Q000187:drug effects*; D005260:Female; D005905:Glyburide / Q000494:pharmacology*; D007103:Immobilization; D009200:Myocardial Contraction / Q000187:drug effects; D009924:Organ Culture Techniques; D051381:Rats; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D014664:Vasodilation / Q000187:drug effects*
D000889:Anti-Arrhythmia Agents; D000254:Sodium-Potassium-Exchanging ATPase; D005905:Glyburide