">&ensp;</span>state <span  title="" class="an ">&ensp;</span>activation <span  title="" class="an ">&ensp;</span>curve <span  title="" class="an ">&ensp;</span>of <span  title="" class="an ">&ensp;</span><span  title="CAP" class="an CAP">HCN</span><span  title="" class="an ">&ensp;</span>channels <span  title="" class="an ">&ensp;</span>shows <span  title="" class="an ">&ensp;</span>a <span  title="" class="an ">&ensp;</span>minimal <span  title="" class="an ">&ensp;</span>shift <span  title="" class="an "