Identification of alpha 2 adrenoceptors in the blood vessels of the dental pulp.

Using selective agonists and antagonists of alpha2 adrenoceptors, attempts were made to identify the subtype alpha2 adrenoceptors in the blood vessels of the canine dental pulp. In chloralose-anaesthetized dogs, intra-arterial administration of noradrenaline and guanabenz in different doses produced a dose-related pulpal vasoconstriction which was measured using hydrogen-gas clearance. The vasoconstrictor response to noradrenaline was inhibited by phentolamine, a non-selective alpha adrenoceptor antagonist. The response to guanabenz was inhibited by rauwolscine, a highly selective alpha2 adrenoceptor antagonist. The results demonstrated that alpha2 adrenoceptors are present in the blood vessels of dog dental pulp.