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

详细信息    查看全文

• 作者：Sharma ; Prashant ; Kumar Barthwal ; Manoj ; Dikshit ; Madhu
• 关键词：Polymorphonuclear leukocytes ; Nitric oxide ; Free radicals ; Citrulline ; Calcium modulators ; Hyperoxia ; 2^&prime ; ; 7^&prime ; -Dichlorofluoreseindiacetate
• 刊名：Nitric Oxide
• 出版年：2002
• 出版时间：September, 2002
• 年：2002
• 卷：7
• 期：2
• 页码：119-126
• 全文大小：212 K

文摘

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 120min. 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 15min 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.