ELECTRICAL-STIMULATION OF THE 5TH CRANIAL NERVE IN RABBITS - EFFECTS ON OCULAR BLOOD-FLOW, EXTRA-VASCULAR ALBUMIN CONTENT AND INTRA-OCULAR PRESSURE

The ophthalmic-maxillary trunk of the fifth cranial nerve was electrically stimulated in rabbits. The regional blood flow was measured with radioactively labelled microspheres, the extravascular albumin content with 125I- and 131I-labelled rabbit serum albumin and the intraocular pressure with pressure transducers. The total albumin concentration of the aqueous humor was measured immunoelectrophoretically. Stimulation caused an increase in the blood flow of the whole uvea and in the cutaneous regions innervated by the nerve. The extravascular albumin content was markedly increased in the ciliary processes and the iris but no change was observed in the choroid. The albumin content of the aqueous humor also increased markedly and the intraocular pressure rose by around 80%. Miosis was produced in 15 of 21 eyes. It is concluded that electrical stimulation of the ophthalmic-maxillary trunk of the fifth cranial nerve caused release of an agent or agents which usually induced miosis, vasodilation and breakdown of capillary and epithelial barriers in the eye. Miosis was the least constant effect. Capillary damage did not seem to be related to the vasodilation but the epithelial leakage probably was due to a distension of the ciliary processes caused by an abnormal fluid leakage from the capillaries. © 1979.