uinea <span  title="" class="an ">&ensp;</span>pig <span  title="" class="an ">&ensp;</span>ileum <span  title="" class="an ">&ensp;</span>and <span  title="" class="an ">&ensp;</span>that <span  title="" class="an ">&ensp;</span>specific <span  title="" class="an ">&ensp;</span>antagonists <span  title="" class="an ">&ensp;</span>for <span  title="" class="an ">&ensp;</span>these <span  title="" class="an ">&ensp;</span><span  title="CAP" class="an CAP">NC</span><span  title="" class="an ">&ensp;</span>rec