Effects of intracranial oculomotor nerve stimulation on ocular blood flow in rabbits: Modification by indomethacin

The oculomotor nerve was stimulated intracranially and regional blood flow in the eye was determined by using labelled microspheres. Stereotactic insertion of the electrode and/or electrical stimulation to test its position caused a long-lasting increase in choroidal blood flow. This effect could not be prevented by pretreatment with 20 mg/kg body weight indomethacin. Stimulation of the nerve 10–20 min after the insertion of the electrode caused miosis and a marked reduction in blood flow in the anterior uvea. In the ciliary processes that could be scraped off the iris the blood flow was 24±7% lower than on the control side. In the rest of the iris-ciliary body preparation the flow was reduced by 53±4%. In animals pretreated with indomethacin the corresponding figures were 51±8% and 75±4%, respectively. The results indicate that the stimulation applied caused a vasoconstriction in the anterior uvea which was potentiated by indomethacin. The anatomical basis for this effect and for the long-lasting vasodilation that was produced in the choroid remains unknown.