The negative chronotropic effect of Cs(+) ions on generation of transmembrane potentials in mouse sinoatrial node cells.
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.
Institute of Physiology, Komi Research Centre, Urals Division of Russian Academy of Sciences, Syktyvkar, Russia.
M A
MA
Gonotkov
V A
VA
Golovko
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002586:Cesium / Q000494:pharmacology*; D004594:Electrophysiology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects*; D051379:Mice; D012849:Sinoatrial Node / Q000166:cytology*
D002586:Cesium