Evidence for Alpha2 Adrenergic Receptors in Bovine Cerebral Arteries
Adrenergic innervation to cerebral arteries is thought to play an important role in controlling cerebral blood flow (1). Histochemical studies have revealed high concentrations of norepinephrine and rich adrenergic innervation from the superior cervical ganglion in the adventitia and outer border of the medial layer of cerebral arteries in various species (2,3). Isolated cerebral arteries are contracted by alpha adrenergic agonists in a dose dependent manner and this contraction is blocked by alpha adrenergic antagonists (4,5). Alpha adrenergic receptors have been classified into alpha and alpha2 subtypes (6,7). Sakakibara et al. (8) suggested that contraction of the isolated dog basilar artery is mediated by alpha receptors. In the present study, we attempted to characterize alph2 adrenergic receptors in bovine cerebral arteries using an alpha1 antagonist, [3H]prazosin and an alpha2 antagonist, [3H]yohimbine.
KeywordsCerebral Artery Adrenergic Receptor Superior Cervical Ganglion Alpha Adrenergic Receptor Adrenergic Innervation
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