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S D Kroll J Chen M De Vivo D J Carty A Buku R T Premont R Iyengar 《The Journal of biological chemistry》1992,267(32):23183-23188
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Macrophage oxidation of L-arginine to nitrite and nitrate: nitric oxide is an intermediate 总被引:117,自引:0,他引:117
Previous studies have shown that murine macrophages immunostimulated with interferon gamma and Escherichia coli lipopolysaccharide synthesize NO2-, NO3-, and citrulline from L-arginine by oxidation of one of the two chemically equivalent guanido nitrogens. The enzymatic activity for this very unusual reaction was found in the 100,000g supernatant isolated from activated RAW 264.7 cells and was totally absent in unstimulated cells. This activity requires NADPH and L-arginine and is enhanced by Mg2+. When the subcellular fraction containing the enzyme activity was incubated with L-arginine, NADPH, and Mg2+, the formation of nitric oxide was observed. Nitric oxide formation was dependent on the presence of L-arginine and NADPH and was inhibited by the NO2-/NO3- synthesis inhibitor NG-monomethyl-L-arginine. Furthermore, when incubated with L-[guanido-15N2]arginine, the nitric oxide was 15N-labeled. The results show that nitric oxide is an intermediate in the L-arginine to NO2-, NO3-, and citrulline pathway. L-Arginine is required for the activation of macrophages to the bactericidal/tumoricidal state and suggests that nitric oxide is serving as an intracellular signal for this activation process in a manner similar to that very recently observed in endothelial cells, where nitric oxide leads to vascular smooth muscle relaxation [Palmer, R. M. J., Ashton, D. S., & Moncada, S. (1988) Nature (London) 333, 664-666]. 相似文献
4.
The nature of RNA coded by the only light-strand (L-strand) open-reading frame unidentified reading frame 6 (URF6) was studied by using a variety of single- and double-strand DNA subclones derived from the 3.6-kilobase (kb) cytochrome b (cyt b)-URF5 coding region of the mouse mitochondrial genome. Northern blot experiments using single-strand-specific M13 clones indicate that both the heavy (H) and L strands of this genomic region are symmetrically transcribed and processed into poly(adenylic acid) [poly(A)] RNAs of comparable size. The 1.2- and 2.4-kb RNAs coded by the H strand, putative mRNAs for cyt b and URF5 reading frames, respectively, are derived from a common precursor of 3.6-kb RNA. The L-strand-coded 1.15-kb RNA, on the other hand, is derived from a short-lived precursor of 3.6-kb RNA by a multiple-step processing involving a 2.4-kb intermediate RNA. The S1 nuclease protection experiments using both the 3'- or 5'-end-labeled DNA probes and also affinity-purified 32P-labeled RNA probes indicate that the 1.15-kb RNA maps between the start of the URF6 reading frame (3' end) and a region 590-600 nucleotides to the 5' end of this reading frame. The 1.15-kb RNA thus contains the entire URF6 coding sequence and an about 590-nucleotide-long 3' untranslated region. The molar abundance of the three mRNAs in the steady-state mitochondrial RNA varies markedly. The 1.15-kb URF6 mRNA is only one-tenth the level of 1.2-kb cyt b mRNA, although it is nearly as abundant as the 2.4-kb URF5 mRNA.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
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The effects of protein malnutrition on responsiveness of macrophages to proteosepeptone stimulation and on their chemical
composition were investigated. Relative number of resident macrophages in rat peritoneal cavity was reduced by about 50 %
during 4 weeks on 3 % protein diet. Similarly, decreased migration capacity of the circulating macrophages to the peritoneal
exudate in response to the stimulant, was observed in protein-fasted rat compared to that in the 20 % protein-fed group. Further,
the chemical composition of the isolated elicited cells was determined. Total proteins, sugars, lipids and nucleic acids were
significantly low in the cells isolated from protein-deficient animals, though the cell size was not affected. However, cholesterol:
phospholipid molar ratios were distinctly higher than that in control and increased progressively in the 3 and 8 % protein-fed
animals. The implications of these structural changes in macrophages on their functional capability are discussed 相似文献
6.
A recent study from our laboratory indicated additional tissue injury during rewarming of a cooled rabbit leg. Oxygen-derived free radicals were believed to play a role in such "rewarming injury." Since free radicals may attack membrane phospholipids, we analyzed the phospholipid composition in the leg tissue during cooling and rewarming. Our results indicated significant breakdown of membrane phospholipids, particularly phosphatidylcholine and phosphatidylethanolamine, with a corresponding accumulation of lysophosphatidylcholine and nonesterified fatty acids. Quinacrine, a phospholipase inhibitor, was able to preserve membrane phospholipids during rewarming of the cooled leg. Rewarming of cooled tissue was also accompanied by additional tissue injury, as evidenced by the increased release of lactic acid dehydrogenase and creatine kinase, as well as enhanced lipid peroxidation, as evidenced by increased malonaldehyde formation. Quinacrine reduced the release of these intracellular enzymes and decreased lipid peroxidation, suggesting its efficacy as a therapeutic agent against hypothermic injury. 相似文献
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Opiate actions on mesocortical dopamine metabolism in the rat 总被引:3,自引:0,他引:3
The actions of parenteral morphine were examined with regard to dopamine metabolism in the mesocortical dopaminergic pathways of the rat. The effects of morphine on dopamine metabolism in the prefrontal, cingulate, pyriform and entorhinal cortices were compared with the actions of morphine on the metabolism of dopamine in the striatum and olfactory tubercle. In all tissues, except the entorhinal cortex, morphine significantly elevated the dopamine metabolites dihydroxphenylacetic acid and homovanillic acid. These data, along with previous studies of various pharmacological agents, clearly indicate that the mesocortical dopaminergic projections possess unique opioid and non-opioid regulatory inputs. 相似文献
9.
Effect of storage, photoperiod and mechanical scarification on seed germination in Ocimum americanum
Dilip Amritphale Y. K. Mukhiya J. C. Gupta Shamanta Iyengar 《Physiologia plantarum》1984,61(4):649-652
Seeds of Ocimum americanum L. display an absolute light requirement for germination. The minimal length of the daily photoperiod required to induce a high germination decreased with increasing seed age, but the length of the photoperiod under potential control of terminal far-red light inhibition remained unchanged. There was a gradual escape from the far-red inhibition with increase in the length of the photoperiod. Seeds developed flash photosensitivity after the first 13 h photoperiod. Scarification treatment did not allow the seeds to bypass the light requirement, but it enhanced the germination considerably. Under conditions of natural day length in the field, weakening of the testa by sand may abolish the need for a second exposure to light for most of the seed population, thus rendering them non-photoperiodic. 相似文献
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