alpha 2-Adrenoceptors mediate sympathetic vasoconstriction in distal segments of rat tail artery.
Proximal and distal segments of the tail artery were taken from normotensive Sprague-Dawley rats. Field stimulation (0.3-30 Hz) of periarterial sympathetic nerves elicited vasoconstrictor responses which were antagonized by prazosin (0.1-10 nM) to a much lesser extent in distal than in proximal segments. The selective alpha 2-adrenoceptor antagonist idazoxan (100 nM) alone had little effect in either segment; however in combination with prazosin vasoconstrictor responses were markedly reduced in distal segments. It is concluded that postjunctional alpha 2-adrenoceptors substantially mediate sympathetic vasoconstriction in distal segments of Sprague-Dawley rat tail artery and that this in vitro preparation may be a useful model for elucidating and extending data obtained in vivo in the human forearm circulation (Van Brummelen et al., 1983).
Medgett
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D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D001158:Arteries / Q000294:innervation; D004146:Dioxanes / Q000494:pharmacology; D019329:Idazoxan; D066298:In Vitro Techniques; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000294:innervation*; D011224:Prazosin / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000502:physiology*; D013564:Sympathetic Nervous System / Q000502:physiology*; D013623:Tail / Q000098:blood supply; D014661:Vasoconstriction / Q000187:drug effects
D000317:Adrenergic alpha-Antagonists; D004146:Dioxanes; D011942:Receptors, Adrenergic, alpha; D011224:Prazosin; D019329:Idazoxan