Nitric oxide synthases in mammals

Abstract

bound pterin to the tetrahydro form (BH4). Cit, citrulline; cyt c, cytochrome c.

Inhibition of nitric oxide synthase by nasal decongestants

“…Differences in the NOS systems have been found between cell types of animals of different species and humans [9]. Therefore, the results cannot be directly extrapolated to human upper airways.…”

“…The inducible form of NOS (iNOS), which is Ca 2+ -independent, can be found in inflammatory cells, such as macrophages, after they are activated by proinflammatory mediators like oxidants, cytokines and endotoxins. Once this enzyme is expressed it produces significantly larger amounts of NO for longer periods than the constitutive isoform does [8,9]. NO is known to play an important role in airway function and seems to be implicated in the pathophysiology of several lower airway diseases.…”

Intrinsic radiosensitivity of human pancreatic tumour cells and the radiosensitising potency of the nitric oxide donor sodium nitroprusside

“…Indeed, these alternative effects have been already described for the vasodilators flunarizine and hydralazine (discussed in Teicher et al, 1993). Another limitation to the use of NO prodrugs may arise from their side-effects on the nervous systems, which is responsive to low concentrations of NO (Knowles and Moncada, 1994). Therefore, the concentrations of NO required for radiosensitisation may be difficult to obtain in vivo for any NO donor.…”

“…The poor response rates to external beam radiotherapy may be explained by the proximity of many dose-limiting organs and possibly by intrinsic and hypoxia-induced radioresistance as well. The latter factor is of considerable interest, because hypoxic cells can be specifically targeted by electron-affinic compounds such as nitroimidazoles and bioreductive cytotoxins (Adams, 1992).Nitric oxide (NO) is a relatively long-life radical generated endogenously by nitric oxide synthases, and has been implicated in signal transduction in the nervous and vascular system and as a cytotoxin in pathophysiological processes related to cellular immunity and hypoxia -reoxygenation injury (Knowles and Moncada, 1994). NO, in gaseous form or released chemically from the NONOate complex DEA/ NO, has also been shown to radiosensitise hypoxic cells.…”

“…Nitric oxide (NO) is a relatively long-life radical generated endogenously by nitric oxide synthases, and has been implicated in signal transduction in the nervous and vascular system and as a cytotoxin in pathophysiological processes related to cellular immunity and hypoxia -reoxygenation injury (Knowles and Moncada, 1994). NO, in gaseous form or released chemically from the NONOate complex DEA/ NO, has also been shown to radiosensitise hypoxic cells.…”