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Abstract
Many techniques are available for assessing ocular vascular reactivity, but few are totally devoid of modulating factors such as reflex adjustments in vascular tension or changes in arterial or intraocular pressures. This report describes the use of isolated long posterior ciliary arteries (LPCA) from bovine eyes to demonstrate the direct vascular effects of several vasoactive agents implicated in the control of local blood flow. The LPCA is most sensitive to serotonin, followed by norepinephrine and histamine; the greatest contractile responses were elicited by serotonin and histamine. Potassium causes relaxation at low concentrations, but contraction at higher concentrations. No responses were elicited with isoproterenol, implying a lack of β-adrenergic receptors in these vessels. The potential significance of these agents in the control of ocular blood flow is discussed.