Capillary endothelial-cell mitogenic activity in experimental branch vein occlusion.

Since the 1940s, the major hypothesis regarding the stimulus for neovascularization occurring in diabetic retinopathy and other "ischemic" retinopathies has involved the release of a soluble angiogenic factor from the ischemic retina. We sought to test this by measuring the endothelial mitogenic activity that could be extracted from an ischemic retina caused by branch vein occlusion in the cat. We found that the extractable endothelial-cell mitogenic activity from normal retinal areas was similar to that in ischemic areas at 1, 2, and 7 days after the occlusion. In the area of occluded veins, the oxygen partial pressure was low (7 +/- 7 mm Hg) compared with the normal value (23 +/- 8 mm Hg). The data did not show any increase in soluble mitogenic factor release from the ischemic retina versus normal retinal areas under the conditions of this experiment.