Postjunctional α2-adrenoceptors in blood vessels of human nasal mucosa
Tóm tắt
Human nasal mucosa has various types of blood vessels and is a good tissue for demonstrating receptors for many vasoactive substances, including α-adrenoceptors. In contrast to the large contractile response induced by α2-agonists, our studies have shown that α2-agonists produce a small maximal contraction. This α2-induced response was easily blocked by α1-antagonists, indicating that it is evoked, at least partially, by the stimulation of α1-adrenoceptors. Noradrenaline (NA)-induced contractions could not be abolished by either α1- or α2-antagonists alone, but were almost completely blocked by the combination of both antagonists. This suggests the presence of postjunctional α2-adrenoceptors. The low-maximal responsiveness to α2-agonists and calcium independency of NA-induced contractions were distinct from our former results obtained on canine nasal specimens.
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