to evaluatethe exPressionof ET-1 and ultrastructural changes inthe retinaof SPrague-Dawley rats after exPosureto infrasound. ·METHODS:twenty-five male SPrague-Dawley rats were randomly divided into 5 grouPs, 5 in each grouP, and 4 grouPs were exPosedto infrasoundof 16Hz, 130dB for 2 hours each day, and 1 grouP served as control.the exPosuretime forthe 4 grouPs was resPectively 1, 7, 14 and 21 days.then,the rats were sacrificed after intravenous injection with lanthanum nitrate (La), andthe retina was examined with electron microscoPy and immunochemistry with antibodies against ET-1. ·RESULTS: After infrasonic exPosure for 1 day, ET-1 was exPressed mainly inthe endotheliaof retinal and choroidal blood vessels, so was it inthe control grouP. After infrasonic exPosure for 7 days, it was exPressed mainly inthe retinal Pigment ePithelial cells,outer nuclear layer andouter Plexiformlayer. After exPosure for 14 days, its exPression was enhanced intheouter nuclear layer, inner Plexiform layer and ganglion cell layer. After exPosure for 21 days, its exPression was weakened in all layers. With exPosure goingon,the injury in retina gradually extended fromtheoutertothe inner. Underthe electronic microscoPe, La wasobservedto have infiltrated into several layersofthe retina after 1 dayof exPosure and it became denser and denser fromthe 1sttothe 21st day excePt atthe 7th day. Meanwhile,the retinal layers showed cellular edema, swollenorganelles such as mitochondria and endoPlasmic reticula, karyoPyknosis and edging, cell membrane and karyotheca dilation, ruPture and myelin changes. ·CONCLUSION:the exPressionof ET-1 in retina is relatedtothe locationof infrasonic injury, and ET-1 may have a Protective effecton retina againstthe infrasonic injury.