Біологічні студії (Apr 2014)
Comparative analysis of the mechanokinetics of contractile activity of myometrium smooth muscles under calixarene C-99 and ouabain action
Abstract
It is known that calix[4]arene with cipher C-99 selectively and with high affinity capable of inhibiting the Na+, K+-ATPase (compared with a known inhibitor of this enzyme – ouabain) of smooth muscle cells plasma membrane preparations. Therefore, the work was carried out comparative study of influence calixarene C-99 and ouabain (both compounds at a concentration of 10 µM) on spontaneous and caused (high-potassium solution, acetylcholine and oxytocin) contractions of the rat uterus longitudinal smooth muscles. Contractile activity studied tensometrically in isometric mode, analysis of the kinetic properties of contractions performed the calculation of the normalized maximal velocity of contraction (Vnс) and relaxation (Vnr) phases. Ouabain and calixarene C-99 unidirectional changed the spontaneous contractile activity, causing a significant increase in the amplitude and frequency of contractions. Both compounds are equally causing decrease in maximum force oxytocin-evocked (0.1 IU) contractions, also causing acceleration the growth of force (this is reflected in the increasing parameter Vnc). Also calixarene C-99 and ouabain not change the maximum force of acetylcholine- (10 µM) and K+-induced (80 mM) contractions and do not affect the character of growth of contractile responses (Vnc parameter remains unchanged). The responsiveness of relaxation velocity for the actions ouabain and calixarene C-99 depend on the nature of stimulation: in the case of oxytocin-evocked contractions it decreased and for K+-induced contractions – remained unchanged. Thus, ouabain and calixarene C-99 unidirectional changed the mechanokinetical parameters of spontaneous, agonist- and depolarization-induced contractions of rat myometrium. These results suggest that the effect of calixarene C-99 on the rat uterus smooth muscles is similar to the action of ouabain and is caused by inhibition of plasma membrane sodium pump.
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