Russian Journal of Biological Physics and Chemisrty Russian Journal of Biological Physics and Chemisrty АКТУАЛЬНЫЕ ВОПРОСЫ БИОЛОГИЧЕСКОЙ ФИЗИКИ И ХИМИИ 2499-9962 54589 МЕДИЦИНСКАЯ БИОФИЗИКА И БИОФИЗИЧЕСКАЯ ХИМИЯ MEDICAL BIOPHYSICS AND BIOPHYSICAL CHEMISTRY МЕДИЦИНСКАЯ БИОФИЗИКА И БИОФИЗИЧЕСКАЯ ХИМИЯ The potassium channels play a pivotal role in formation of automaticity in the mouse sinoauricular node Калиевые каналы играют ключевую роль в формировании автоматии в синоаурикулярном узле мыши Головко В А Golovko V A golovko@phisiol.komisc.ru Козловская А В Kozlovskaya A V Институт физиологии ФИЦ «Коми НЦ УрО РАН» ru Institute of Physiology, Komi Sceince Centre URD RAS ru Сыктывкарский государственный университет им. П. Сорокина ru P. Sorokin Syktyvkar State University ru 25 12 2020 25 12 2020 5 4 704 708 20 12 2020 20 12 2020 https://rusjbpc.ru/en/nauka/article/54589/view

Исследовали роль калиевых токов в формировании морфологии потенциалов действия клеток истинного водителя ритма (ИВР) в синоаурикулярном (СА) узле мыши. Биофизические параметры регистрировали у клеток спонтанно сокращающихся полосок миокарда с помощью микроэлектродной техники. Фармакологический анализ проводили путем аппликации специфических блокаторов калиевых каналов, а также неселективного канала тока, активируемого гиперполяризацией HCN. Установили, что клетки ИВР располагаются вдоль артерии СА-узла и отличаются самой медленной скоростью нарастания потенциала действия (ПД) в фазу 0. Ивабрадин (3 µМ) замедлял частоту генерации ПД на 24% за счет увеличения скорости фазы медленной диастолической деполяризации (МДД). Е-4031 - блокатор быстрого выходяего калиевого тока, I Kr, влиял на длительность и скорость фазы реполяризации, а в концентрации 1 мкМ вызывал увеличение длительности МДД и замедление частоты генерации ПД. Полная блокада I Kr вызвает деполяризацию сарколеммы и прекращение электрической активности. Хроманол 293В блокировал каналы медленного выходящего калиевого тока I Ks. Вклад I Ks в фазу реполяризации составлял 20-30%, а частота генерации ПД замедлялась в среднем на 7%. Проходящий ток I to вносил существенный вклад в частоту генерации ПД клеток СА-узла мыши. Блокатор каналов тока I to (0,5 мМ) вызывал увеличение ДПД20 в среднем на 43%, а в концентрации 5 мМ - на 80%. При этом частота генерации ПД снижалась на 14%. Таким образом, калиевые токи играют ключевую роль в формировании ПД клеток СА-узла мыши и участвуют в модуляции ритма спонтанных сокращений.

The role of potassium currents in the formation of action potential morphology of true pacemaker cells in the mouse sinoauricular node (SAN) was studied. Biophysical parameters were recorded in cells using microelectrode. Pharmacological analysis was performed by applying specific potassium channel blockers, as well as a non-selective current channel activated by hyperpolarization HCN. It was found that the true pacemaker cells are located along the SAN artery and differ in the slowest velocity of action potential (AP) upstroke dV/dtmax (≈3 V/s). Ivabradine (3 µmol) decreased the frequency of AP generation by 24% due to an increase in the duration and velocity of the slow diastolic depolarization (SDD) phase. E4031- blocker of fast inward potassium current, I Kr, affected the duration and velocity of the repolarization phase. E4031 (1 µmol) caused an increase in SDD duration and a decreased in the frequency of AP generation. Complete inhibition of I Kr channels can cause depolarization of the sarcolemma and blocks of electrical activity. Chromanol 293B blocked the channels of slow inward potassium current, I Ks. The contribution of IKs to the repolarization phase was 20-30%. The frequency of AP generation slowed down by an average of 7%. The I to current made a significant contribution to the frequency of AP generation in SAN cells of the mouse. 4-AP aminopyridine - blocker of I to channels (0.5 mmol) caused an increase in AP duration by an average of 43%, and in the concentration of 5 mmol - by 80%. At the same time, the frequency of AP generation decreased by 14%. Thus, potassium currents play a key role in the formation of AP in the mouse CA node cells and participate in the modulation of the rhythm of spontaneous contractions.

 синоаурикулярный узел потенциал действия медленная диастолическая деполяризация калиевые токи блокаторы мышь sinoauricular node action potential slow diastolic depolarization potassium currents blockers mouse

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