Tetrahydrobiopterin in nitric oxide synthase

Tetrahydrobiopterin and endothelial nitric oxide synthase activity.

Tetrahydrobiopterin and endothelial nitric oxide synthase uncoupling.

Tetrahydrobiopterin and Endothelial Nitric Oxide Synthase Uncoupling To the Editor: Gao et al1 reported that oral administration of folate, the tetrahydrobiopterin (H4B) precursor, attenuated endothelial NO synthase (eNOS) uncoupling in abdominal aortic aneurysm. The beneficial effects of H4B supplementation in endothelial dysfunction are beyond dispute, but in vivo demonstration of eNOS (un)co...

Tetrahydrobiopterin: important endothelial mediator independent of endothelial nitric oxide synthase.

Tetrahydrobiopterin (BH4), an essential cofactor for diverse cellular processes, is present in almost every cell or tissue of higher organisms. BH4 has well-defined functions in terms of enzymatic activities (BH4 is a crucial cofactor for the aromatic amino acid hydroxylases and all isoforms of nitric oxide synthase [NOS]) but has other less-defined functions in cells. BH4 is a growth or prolif...

Dexamethasone, tetrahydrobiopterin and uncoupling of endothelial nitric oxide synthase

OBJECTIVE To find out whether dexamethasone induces an uncoupling of the endothelial nitric oxide synthase (eNOS). METHODS & RESULTS A major cause of eNOS uncoupling is a deficiency of its cofactor tetrahydrobiopterin (BH4). Treatment of human EA.hy 926 endothelial cells with dexamethasone decreased mRNA and protein expression of both BH4-synthesizing enzymes: GTP cyclohydrolase I and dihydro...

Tetrahydrobiopterin protects against guanabenz-mediated inhibition of neuronal nitric-oxide synthase in vitro and in vivo.

It is established that guanabenz inhibits neuronal nitric-oxide (NO) synthase (nNOS) and causes the enhanced proteasomal degradation of nNOS in vivo. Although the time- and NADPH-dependent inhibition of nNOS has been reported in studies where guanabenz was incubated with crude cytosolic preparations of nNOS, the exact mechanism for inhibition is not known. Moreover, even less is known about how...