Prejunctional modulation of norepinephrine release in the human iris-ciliary body.

摘要: Purpose. To characterize the prejunctional mechanisms that control impulse-evoked release of norepinephrine in isolated, superfused human iris-ciliary body. Methods. Human body tissue segments were preincubated with 3 H-norepinephrine, and electrically-stimulated vitro to evoke discharge H-norepinephrine. The effects modulators on evoked s H-norepinephrine overflow evaluated. Results. Stimulation-evoked (but not spontaneous) was inhibited by a2-adrenergic, muscarinic, dopaminergic, neuropeptide Y, prostaglandin agonists enhanced angiotensin II. Agonist-induced blocked selective antagonists, where available. Yohimbine atropine alone output, suggesting a 2-adrenergic muscarinic receptors undergo tonic activation endogenously released neurotransmitters. Conclusions. ocular sympathetic nerves express inhibitory cv2-adrenergic, prostaglandin, Y facilitator)' II These may be useful targets for pharmacologic manipulation adrenergic system vivo. Invest Ophthalmol Vis Sci 1993;34:2790-2793.