Responses of the uterine circulation to sympathetic nerve stimulation.
Pregnant and non-pregnant sheep uteri were perfused in situ with arterial blood at a constant flow rate. Unilateral stimulation (1-2 ma, u ms pulse) of the distal end of the severed sympathetic chain (L3-L4) at frequencies between 5 and 25 Hz produced a graded increase in uterine artery pressure in both horns. At 25 Hz, pressure in the horn ipsilateral to the stimulated sympathetic chain increased by 28 +/  2% in four pregnant animals and 32 +/ 5% in six non-pregnant ewes. The response of the contralateral horn was significantly smaller than that of the ipsilateral horn (P less than or equal to 0.05). The response was alpha-mediated since it was abolished by local injection of dibenzyline into the middle uterine artery. The responses of the pregnant and non-pregnant animals were similar, indicating that pregnancy did not alter the alpha-adrenergic responses of the uterine vasculature.
D000818:Animals; D001158:Arteries / Q000294:innervation; D001794:Blood Pressure / Q000187:drug effects; D004558:Electric Stimulation; D005260:Female; D009638:Norepinephrine / Q000494:pharmacology; D011247:Pregnancy; D012756:Sheep; D013564:Sympathetic Nervous System / Q000502:physiology*; D014599:Uterus / Q000098:blood supply*; D014661:Vasoconstriction / Q000187:drug effects
D009638:Norepinephrine