A vasorelaxing factor is released from mouse retinal tissue

The present study aimed to demonstrate the release of a retinal relaxing factor (RRF) from the retina of mice and to investigate the identity of the RRF. Ring segments of a mouse aorta were mounted in a small vessel myograph. The relaxing influence of mouse retinal tissue was assessed by placing a retina in close proximity to the precontracted aorta. This elicited reliable and reproducible relaxations in the aorta. Both the nitric oxide (NO) synthase inhibitor N(omega)-nitro-L-arginine and the soluble guanylyl cyclase inhibitor 1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one had no effect on the RRF response. Also the cyclooxygenase inhibitors indomethacin and sodium diclofenac failed to affect the retina-induced relaxations. Acute hypoxia largely enhanced retina-induced relaxations. It is concluded that mouse retinal tissue releases an RRF, that the mouse RRF response is not mediated by NO or prostanoids and that the mouse RRF response is profoundly influenced by hypoxia.