Modulation of mitochondrion-mediated oxidative stress by nitric oxide in human placental trophoblastic cells

Abstract

Intracellular hydroperoxide generation in cultured human placental trophoblastic cells (HPTCs) was quantitatively monitored in the presence or absence of an NO synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME, 1 mM), by digital microfluorography with use of carboxydichlorofluorescein, a hydroperoxide-sensitive fluorogenic probe. In the absence of L-NAME, HPTCs displayed a time-dependent gradual elevation of the fluorescence, suggesting the ability to produce oxidants spontaneously. In the presence of L-NAME, however, the fluorescent response in these cells increased further; the oxidative impact elicited by L-NAME treatment for 30 min was equivalent to that induced by application of 230 microM tert-butyl hydroperoxide for 5 min. This oxidative process was completely blocked by rotenone, a reagent that interferes with electron entry into complex I of the mitochondrial respiratory chain. On the other hand, antimycin A, which blocks mitochondria at the distal site of the ubiquinone pool, potentiated the L-NAME-induced oxidative change. These findings suggest that constitutive levels of nitric oxide production contribute to regulation of mitochondrion-derived intracellular oxidant generation in HPTCs.

Expression and Localization of Heme Oxygenase in Human Placental Villi

“…Furthermore, HO also catalyzes the formation of biliverdin and its product bilirubin, both of which are powerful antioxidants (27). There has been a previous study on antioxidant roles of NO in modulation of oxidative stresses in human placental trophoblastic cells (28). Therefore, HO-catalyzed production of biliverdin/bilirubin and NOS-catalyzed synthesis of NO serve as a protection of placental cells against oxidative injury.…”

Alteration of nitric oxide synthase activity upon oxidative stress in cultured retinal cells

“…On one hand, NO · has been implicated in long-term potentiation, memory, and learning (Bruhwyler et al, 1993). NO · has also been suggested to control intracellular oxidative stress by eliminating the oxidants derived from the mitochondria (Goda et al, 1996) or to serve as an antioxidant in the presence of t-butyl hydroperoxide or cumene hydroperox-ide (Wink et al, 1995). On the other hand, the neurotoxicity of NO · has been evident due to its effect on the mitochondrial respiratory chain, by inhibiting cytochrome oxidase (Bolaños et al, 1994(Bolaños et al, , 1995, or through the effect of peroxynitrite in the oxidation of thiol groups (Salgo et al, 1995;Karoui et al, 1996) and inhibition of glutamate transport (Trotti et al, 1996).…”

Biological chemistry of reactive oxygen and nitrogen and radiation-induced signal transduction mechanisms

“…The importance of NO in regulating cellular ROS levels is underlined by the recent identification of a Ca 2 þ -activated NOS isoform in the mitochondria of cells (Kanai et al, 2001;Elfering et al, 2002). Pharmacological inhibition of cellular NOS stimulates O 2 À production, and NO scavengers induce cellular oxidative stress (Niu et al, 1996;Goda et al, 1997;Janssen et al, 1998a, b).…”