The effects of neonatal 6-hydroxydopamine induced sympathectomy on response inhibition in extinction.

Superfused helical strips of canine anterior mesenteric arteries and veins and canine dorsal metatarsal veins contract in response to prostaglandin B₂ (PGB₂). Reserpine pretreatment and phentolamine reduce the constrictor response to PGB₂. PGB₂ enhances the contractile responses of these preparations to potassium, barium and norepinephrine. PGB₂ also produced a shift to the left in the duration of the barium response curve. The data presented demonstrate that PGB₂ is not an inactive metabolite of PGA₂ metabolism but possesses potent constrictor activity probably dependent on release of norepinephrine from adrenergic nerves. Furthermore, PGB₂ enhances the responses of vascular smooth muscle to vasoactive stimuli.