Ex vivo pharmacology of surgical samples of the uterosacral ligament. Part II: Effects of oxytocin and relaxin on arteries and vascular plexus.
The uterosacral ligament (USL) contains prominent vessels, the function of which is unknown. Here we study the relationship between smooth muscle of the USL and the vascular bundles. Native samples of arteries and vascular bundles were mounted in a perfusion chamber under the stereomicroscope. The effects of noradrenalin, carbachol, oxytocin, and relaxin were monitored by digital time-lapse video and quantified by image processing. Arteries were adrenergic and the smooth muscle in the adventitia cholinergic. Relaxin-2 shifted the dose response curve of noradrenalin to the right and widened the arterial lumen within 30 min. Oxytocin induced contraction of the adventitial smooth muscle leading to a slow opening of the artery. In a vascular bundle the differential pattern of both reactivities was demonstrated. In the USL the smooth muscle extends into the adventitial layer of blood vessels and forms a functional unit with the vascular plexus, which is regulated by relaxin and oxytocin.