function suscriptores_feedburner($mifeed) {
    $url = "https://feedburner.google.com/api/awareness/1.0/GetFeedData?uri=$mifeed";
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_URL, $url);
    $data = curl_exec($ch);
    curl_close($ch);       
    if ($data) {
        preg_match('/circulation=\"([0-9]+)\"/',$data, $matches);
        if ($matches[1] != 0)
            $fb['count'] = $matches[1];
        $fb['lastcheck'] = mktime();
        update_option("feedburnersubscribecount",$fb);
    }
    $feed = $fb['count'];
    return $feed;
}
// Modo de uso
echo suscriptores_feedburner('aqui insertais el nombre cuenta de vuestro feedburner');