Increase in aqueous humour protein concentration induced by oculomotor nerve stimulation in rabbits

Vasomotor effects of facial nerve stimulation: noncholinergic vasodilation in the eye

The effect of facial nerve stimulation on ocular blood flow was studied in rabbits. The intracranial part of the facial nerve was stimulated electrically and the regional blood flow was measured with labelled microspheres. Effects on the intraocular pressure were determined in a separate series of experiments. Stimulation increased choroidal blood flow by about 200%. The blood flow of the iris and the ciliary processes also increased. The blood flow of the eyelids and the nictitating membrane increased by approximately 1000%, and the blood flow of Harder's gland increased by about 200%. The blood flow of the tongue and the submandibular gland also increased. The increase in the uveal blood flow could not be abolished by a cholinergic or ganglionic blockade. Ganglionic blockade abolished most of the increase in the blood flow of the eyelids, nictitating membrane and Harder's gland; the cholinergic blockade seemed less effective. The intraocular pressure increased with a mean value of 6 mmHg during optimal (20-30 Hz) stimulation. The increase could not be prevented by cholinergic blockade. Much of the increase in uveal blood flow seemed to be caused by stimulation of unconventional nerves. It is suggested that these nerves may be peptidergic using VIP as a transmitter and lacking a hexamethonium sensitive synapse between the site of stimulation and the eye. Their nature--afferent or efferent--remains unknown. A great part of the increase in blood flow of the eyelids, nictitating membrane and Harder's gland seemed to be due to other mechanisms involving nerves with a peripheral synapse.

Consensual reactions to anterior chamber paracentesis in the rabbit

A consensual reaction was consistently obtained in rabbits subjected to unilateral paracentesis. On fluorescein angiography of the anterior segment, we observed that this consensual reaction consisted of a slight to moderate dye extravasation from the ciliary processes into the aqueous. Aspirin usually, but not always, inhibited this reaction. Retrobulbar injection of anesthesia to the injured eye always blocked the consensual response, as did phenoxybenzamine injected intravenously before the paracentesis. We concluded that consensual responses are more efficiently inhibited by nerve-blocking agents than by prostaglandin inhibitors. These results suggest that the interocular pathway mediating consensual responses is probably neural and not caused by prostaglandins released into the general circulation.