Increased airway pressure in response to xylazine is inhibited by both atipamezole and atropine in sheep.

The effect on airway pressure of xylazine alone or following the administration of atipamezole or atropine was studied in 31 halothane-anaesthetized sheep. Xylazine produced a significant increase in airway pressure which lasted for at least 30 min. This effect was inhibited by both atipamezole and atropine. The results suggest that the xylazine-induced increase in airway pressure in sheep is alpha 2-adrenergically mediated. Moreover, activation of central alpha 2-adrenoceptors leading to vagal stimulation may be involved.