sp;</span>less <span  title="" class="an ">&ensp;</span>sensitive <span  title="" class="an ">&ensp;</span>to <span  title="" class="an ">&ensp;</span>blockade <span  title="" class="an ">&ensp;</span>of <span  title="" class="an ">&ensp;</span>N <span  title="" class="an ">&ensp;</span>and <span  title="" class="an ">&ensp;</span>P <span  title="" class="an ">&ensp;</span>Q <span  title="" class="an ">&ensp;</span>type <span  title="" class="an ">&ensp;</span>channels <span  title="" class="an ">&ensp;</sp