Alpha 1-adrenoceptor subtype mediates norepinephrine-induced contraction of the rabbit isolated ovarian artery.
The interactions between selective alpha-adrenoceptor agonists and antagonists were studied in the rabbit isolated ovarian artery in an attempt to characterize the alpha-adrenoceptor subtype present in the smooth muscle of this vessel. Norepinephrine, epinephrine, and phenylephrine, but not clonidine or BHT-920, contracted the ovarian artery in a concentration dependent manner. The rank order of potency was epinephrine greater than norepinephrine greater than phenylephrine. The contractions were competitively antagonized by prazosin, phentolamine, and yohimbine. However, prazosin and phentolamine were approximately 100-500 times more potent than yohimbine against norepinephrine and phenylephrine. Observations were unchanged when arterial segments were used after endothelial removal. Norepinephrine-induced contractions of the ovarian artery were relatively resistant to blockade by diltiazem. The results suggest that exclusively alpha 1-adrenoceptors are present in vascular smooth muscle cells of the ovarian artery, whose activation operates through a mechanism relatively independent of Ca2+ influx into the smooth muscle cells.
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D001158:Arteries / Q000187:drug effects / Q000294:innervation; D004110:Diltiazem / Q000494:pharmacology; D005260:Female; D066298:In Vitro Techniques; D009638:Norepinephrine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D010053:Ovary / Q000098:blood supply*; D011817:Rabbits; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects*; D014661:Vasoconstriction / Q000187:drug effects*
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D011942:Receptors, Adrenergic, alpha; D004110:Diltiazem; D009638:Norepinephrine