tle="" class="an ">&ensp;</span>depolarizing <span  title="" class="an ">&ensp;</span>voltage <span  title="" class="an ">&ensp;</span>steps <span  title="" class="an ">&ensp;</span>from <span  title="" class="an ">&ensp;</span>to <span  title="" class="an ">&ensp;</span>m <span  title="" class="an ">&ensp;</span>V <span  title="" class="an ">&ensp;</span>low <span  title="" class="an ">&ensp;</span>voltage <span  title="" class="an ">&ensp;</span>activated <span  title="" class="an ">&ensp;</span><span  ti