Vascular effects of calcitonin gene-related peptide (CGRP) and cholecystokinin (CCK) in the monkey eye.

The effects of cholecystokinin (CCK) and calcitonin gene-related peptide (CGRP) on ocular blood flow were studied in monkeys using the labelled microsphere method. Intracameral administration of 800 pmole CGRP increased the blood flow significantly in the conjunctiva, ciliary body and sclera. There was no significant change in the choroid and retina. CCK-33 (800 pmole) caused no significant effects on the blood flow in the tissues examined, when compared to the control eyes. A miotic response was however noted, consistent with previous results. Neither peptide caused significant changes in the intraocular pressure. These results suggest that CGRP has a vasodilatory effect in some parts of the monkey eye, whereas CCK-33 is a miotic with no marked effect on ocular blood flow.