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Abstract
BACKGROUND/AIMS Endothelium dependent vasodilatation is an important regulator of blood flow to the eye but its role has not been investigated in vessels supplying the ciliary body. This study assessed the role of the endothelium in modulating vasoconstrictor responses of the intraocular bovine anterior ciliary artery.
METHODS Bovine anterior ciliary arteries (n=33) were mounted in a myograph, containing physiological salt solution at 37°C, for isometric force measurement. Cumulative concentration-response curves were obtained to the constrictor agonists 5-hydroxytryptamine (5-HT), noradrenaline, phenylephrine, prostaglandin F2α, endothelin-1, and KCl in both endothelium intact and denuded arteries.
RESULTS All vasoconstrictors produced sustained contractile responses which were unaffected by the removal of the endothelium. Responses to 5-HT were also unaffected by inhibition of nitric oxide synthase.
CONCLUSION These results indicate that neither agonist stimulated nor basal release of nitric oxide from the endothelium modulates responses to vasoconstrictor agonists in the isolated bovine anterior ciliary artery when measured in a no flow isometric system.
- anterior ciliary artery
- constrictor agonists
- endothelium
- nitric oxide