NO synthesis and its regulation in the arachidonic-acid-stimulated rat polymorphonuclear leukocytes

Sharma, Prashant ; Barthwal, Manoj Kumar ; Dikshit, Madhu (2002) NO synthesis and its regulation in the arachidonic-acid-stimulated rat polymorphonuclear leukocytes Nitric Oxide: Biology and Chemistry, 7 (2). pp. 119-126. ISSN 1089-8603

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Nitric oxide (NO) synthesis and free radical generation from polymorphonuclear leukocytes (PMNs) play an important role in several pathological conditions. In the present study, regulation of NO synthesis has been investigated in the unstimulated and arachidonic-acid (AA)-stimulated rat PMNs. L-Citrulline formation or nitrite content was used as a marker of NO synthesis, while AA-induced free radical generation was assessed by flow cytometry using a dye, 2',7'-dichlorofluoreseindiacetate. L-Citrulline formation in the unstimulated PMNs increased in a time-dependent manner for up to 120 min. The increase was significantly less (25-55%) in AA-stimulated PMNs at all the time points. AA-induced free radical generation was maximum during the first 15 min followed by a time-dependent decrease. Interestingly, similar experiments under hyperoxic conditions did not exhibit any decrease in L-citrulline and nitrite formation after AA stimulation even though the free radical generation further increased. Scavenging or inhibition of free radicals by several types of interventions increased NO generation from AA-stimulated PMNs. The results of the present study suggest that the availability of oxygen, a common substrate for both NADPH oxidase and NOS, can inversely affect the synthesis of NO and PMNs seem to prefer oxygen utilization over NO synthesis for free radical generation.

Item Type:Article
Source:Copyright of this article belongs to Elsevier Science.
Keywords:Polymorphonuclear Leukocytes; Nitric Oxide; Free Radicals; Citrulline; Calcium Modulators; Hyperoxia; 2', 7'-Dichlorofluoreseindiacetate
ID Code:9587
Deposited On:02 Nov 2010 11:50
Last Modified:09 Feb 2011 05:49

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