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 labeled 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 stimulation applied caused a vasoconstriction in the anterior uvea which was potentiated by indomethacin. The anatomic basis for this effect and for the long-lasting vasodilation that was produced in the choroid remains unknown.