Oxidative stress-induced apoptosis of endothelial cells

Endothelial cells (ECs) are subjected to oxidative stress during many patho logical processes, including ischemia/reperfusion and general inflammation. In the present study, we examined the effects of oxidative stress on rates of apoptosis in EC cultures. We treated large and microvessel ECs with men adione for 1 h in vitro to simulate the most common physiological form of o xidative stress, exposure to O-2(.-). Capillary ECs were resistant to menad ione-induced apoptosis when compared with large-vessel ECs. Treatment with 35 mu M menadione resulted in an apoptotic rate of similar to 5% in capilla ry EC cultures compared with similar to 45% in large-vessel EC cultures. At higher concentrations of menadione (35-75 mu M), both types of ECs exhibit ed a concentration-related increase in apoptosis. Necrotic cell death only became evident at menadione concentrations ranging from 75-100 mu M for bot h cell types. The timing of the apoptotic response to a 1 h menadione expos ure was very specific. For both EC types, peaks of apoptosis occurred in tw o distinct waves, at 6-8 and 18-22 h after treatment. Analysis of the event s leading up to the first peak of apoptosis indicated that specific matrix metalloproteinases (MMPs) were activated, suggesting that MMPs may be invol ved in initiating the apoptotic process. (C) 2000 Elsevier Science Inc.