Regional regulation of choroidal blood flow by autonomic innervation in the rat.
Regional influences of parasympathetic and sympathetic innervation on choroidal blood flow were investigated in anesthetized rats. Parasympathetic pterygopalatine neurons were activated by electrically stimulating the superior salivatory nucleus, whereas sympathetic neurons were activated by cervical sympathetic trunk stimulation and uveal blood flow was measured by laser Doppler flowmetry. Parasympathetic stimulation increased flux in the anterior choroid and nasal vortex veins but not in the posterior choroid. Vasodilation was blocked completely by the neuronal nitric oxide synthase inhibitor 1-(2-trifluoromethylphenyl)imidazole but was unaffected by atropine. Sympathetic stimulation decreased flux in all regions, and this was blocked by prazosin. Parasympathetic stimulation did not affect vasoconstrictor responses to sympathetic stimulation in the posterior choroid but attenuated the decrease in blood flow through the anterior choroid and vortex veins via a nitrergic mechanism. We conclude that sympathetic alpha-noradrenergic vasoconstriction occurs throughout the choroid, whereas parasympathetic nitrergic vasodilation plays a selective role in modulating blood flow in anterior tissues of the eye.
Steinle
J J
JJ
Department of Molecular and Integrative Physiology and R. L. Smith Mental Retardation Research Center, University of Kansas Medical Center, Kansas City, Kansas 66160-7401, USA.
Krizsan-Agbas
D
D
Smith
P G
PG
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D017776:Autonomic Pathways / Q000502:physiology*; D001794:Blood Pressure / Q000187:drug effects; D002829:Choroid / Q000098:blood supply* / Q000294:innervation* / Q000502:physiology; D004558:Electric Stimulation; D005260:Female; D007093:Imidazoles / Q000494:pharmacology; D017078:Laser-Doppler Flowmetry; D009184:Mydriatics / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D052248:Nitric Oxide Synthase Type I; D010275:Parasympathetic Nervous System / Q000502:physiology; D011224:Prazosin / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012039:Regional Blood Flow / Q000502:physiology; D012169:Retinal Vein / Q000502:physiology; D013564:Sympathetic Nervous System / Q000502:physiology
D000317:Adrenergic alpha-Antagonists; D007093:Imidazoles; D009184:Mydriatics; C098186:1-(2-trifluoromethylphenyl)imidazole; D001285:Atropine; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; C496322:Nos1 protein, rat; D011224:Prazosin