Role of ascorbate in the regulation of nitric oxide generation by polymorphonuclear leukocytes

Sharma, Prashant ; Raghavan, Santhanam A. V. ; Dikshit, Madhu (2003) Role of ascorbate in the regulation of nitric oxide generation by polymorphonuclear leukocytes Biochemical and Biophysical Research Communications, 309 (1). pp. 12-17. ISSN 0006-291X

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We have recently demonstrated that NO-mediated polymorphonuclear (PMN)-dependent inhibition of rat platelet aggregation is significantly enhanced in the presence of ascorbate. Consequently, the present study was undertaken to elucidate the underlying mechanisms involved in ascorbate-mediated potentiation of NO synthesis in PMNs. We observed that ascorbate or its oxidized product, dehydroascorbate (DHA), enhanced NOS activity, as measured by nitrite content, diaminofluorescein fluorescence or conversion of l-[3H]arginine to l-[3H]citrulline in rat, monkey, and human PMNs. The increase in NO generation following ascorbate treatment was due to the intracellular ascorbate as iodoacetamide-mediated inhibition of DHA to ascorbate conversion attenuated the DHA-mediated increase in NO synthesis. The augmentation of NOS activity in the PMN homogenate by tetrahydrobiopterin was significantly enhanced by ascorbate, while ascorbate alone did not influence the NOS activity. Ascorbate-mediated enhancement of NOS activity in the cultured PMNs was significantly reduced in the presence of biopterin synthesis inhibitors. Ascorbate, thus, seems to regulate the NOS activity in the PMNs through tetrahydrobiopterin.

Item Type:Article
Source:Copyright of this article belongs to Elsevier Science.
Keywords:Polymorphonuclear Leukocytes; Nitric Oxide; Tetrahydrobiopterin; Ascorbic Acid; Dehydroascorbic Acid
ID Code:89085
Deposited On:30 Mar 2012 10:38
Last Modified:30 Mar 2012 10:38

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