[Experimental research on choroidal circulation. 1. Effect of sectioning or stimulation of the cervical sympathetic nerve upon choroidal blood flow].

Choroidal blood flow (CBF) was continuously measured with a laser doppler flowmeter (LDF) in 32 pentobarbital-anesthetized cats. A rise in intraocular pressure (IOP) caused a decrease in CBF, but when the IOP increase was slight, it induced a CBF increase. A sustained increase of CBF occurred following sectioning of the cervical sympathetic nerve (CSN) in 7 out of 18 eyes, but no noticeable blood flow change was observed in the remaining 11 eyes. Two different vasomotor responses in CBF were observed in response to electrical stimulation of the peripheral cut end of the CSN; one was a decrease and the other an increase. From the present experiments, decrease of CBF elicited by CSN stimulation is considered to be due to an increase in the activity in vasoconstrictor fibers of choroidal capillary blood vessels, but the exact mechanism of the CBF increase is unknown. Slight changes in position of the LDF probe sometimes alter the vasoresponses, suggesting that the site at which CBF was measured is crucial for investigating the effects of dissection or electrical stimulation of the CSN on CBF.