Homocysteine induces oxidative stress by uncoupling of NO synthase activity through reduction of tetrahydrobiopterin.

Hyperhomocysteinemia is a risk factor for cardiovascular diseases that induces endothelial dysfunction. Here, we examine the participation of endothelial NO synthase (eNOS) in the homocysteine-induced alterations of NO/O(2)(-) balance in endothelial cells from human umbilical cord vein. When cells were treated for 24 h, homocysteine dose-dependently inhibited thrombin-activated NO release without altering eNOS phosphorylation and independently of the endogenous NOS inhibitor, asymmetric dimethylarginine.

Growth rate and phospholipase C activity in cardiac and aortic spontaneously hypertensive rat cells.

The cellular proliferation rate and phospholipase C sensitivity have been compared in various cardiovascular cells cultured from spontaneously hypertensive (SHR) and Wistar-Kyoto rats (WKY). Aortic smooth muscle cells from SHR showed an enhanced proliferation rate under the culture conditions (in the presence of 10% fetal calf serum) and hypersensitivity to the mitogenic action of angiotensin II and serotonin. Phospholipase C activity (determined by measuring the formation of tritiated inositol phosphates from [3H]-myoinositol) triggered by angiotensin II was also higher in these cells than in those from WKY.