The Negative Chronotropic Effect of Cs+ Ions on Generation of Transmembrane Potentials in Mouse Sinoatrial Node Cells

Abstract

Experiments on spontaneously contracting strips from sinoatrial region of the hearts of 2-month-old albino mice showed that cesium (Cs(+)), a blocker of hyperpolarization-activated I(f) current, in a concentration of 1 mM produced the greatest negative chronotropic effect on the duration of diastolic depolarization phase (75%), its rate (59%), and action potential duration (29%). The threshold concentration of Cs(+) was approximately 0.15 mM. In a concentration of about 8.5 mM, spontaneous generation of action potentials stopped. The effect was reversible. Thus, blockade of I(f) current by Cs(+) reduced the rate of action potential generation in cells of mouse sinoatrial node by app. 42% in comparison with controls.

Effects of 4-aminopyridine on action potentials generation in mouse sinoauricular node strips

“…The microelectrode mapping was initiated from the center, between the lateral and medial limbs, by a step of 50 μ m along the SA node artery (Sutyagin et al. 2005 ; Gonotkov and Golovko 2011 ). The murine SAN has a unifocal type of impulse generation and consists of heterogeneous electrical cells similar to other mammals‘ nodes (Golovko 1989 ; Verheijck et al.…”

“…The final SA area preparation was approximately 3 × 2 mm (Fig. 1 ) in size and contained the sinoatrial SAN and a small portion of the surrounding tissue of the right auricle (Gonotkov and Golovko 2011 ). The preparation was fixed with the subendocardial surface face-up in a 5-ml tissue bath with a perfusing Tyrode solution composed of (in mmol/L): 140 NaCl, 10 NaHCO 3 , 5.4 KCl, 1.8 CaCl 2 , 1 MgSO 4 , 10 d glucose, and 5 HEPES (adjusted to pH 7.4 with NaOH) at a rate of 8–10 ml/min.…”

Multidirectional effects of ouabain on automaticity of cells in sinoauricular area in mouse, guinea pig and rabbit

“…У кролика препарат СА узла дополнительно разрезали на две спонтанно сокращающиеся полоски. Потенциалы действия (ПД) регистрировали с помощью стандартной микроэлектродной техники со стороны субэндокарда вдоль артерии СА узла в центре между верхней и нижней полыми венами (31° C) [7]. В качестве селективного блокатора Na + /K + -АТФазы использовали аналог сердечных гликозидов -уабаин (Sigma, Германия).…”