Mechanisms underlying overshoot dilation after sympathetic denervation.
(1) 30--60 sec after transection of the sympathetic chain, the diameter of both femoral artery and vein dilates to approximately 120% of the control diameter ('overshoot dilation'). Vessel diameter subsequently decreases and stabilizes with 5--10 min at a value of 108% of the original ('stabilized dilation'). (2) After treatment with norepinephrine-uptake-blocking drugs (cocaine, imipramine), the transient overshoot dilation is abolished and the diameter 1 min after denervation is identical to that at stabilized dilation. (3) It is proposed that (a) the stabilized rather than the transient overshoot dilation represents the loss of sympathetic control following following denervation and (b) the overshoot dilation reflects a transient decrease in transmitter concentration within the vessel wall, associated with a temporarily undiminished rate of neural reuptake activity persisting even in the absence of transmitter release.
D000818:Animals; D001158:Arteries / Q000294:innervation*; D003042:Cocaine / Q000494:pharmacology; D004285:Dogs; D005260:Female; D005263:Femoral Artery / Q000294:innervation; D005268:Femoral Vein / Q000294:innervation; D007099:Imipramine / Q000494:pharmacology; D008297:Male; D009474:Neurons / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism; D013562:Sympathectomy; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000502:physiology*; D014664:Vasodilation / Q000187:drug effects; D014666:Vasomotor System / Q000502:physiology; D014680:Veins / Q000294:innervation*
D003042:Cocaine; D007099:Imipramine; D009638:Norepinephrine