2-2--(hydroxynitrosohydrazono)bis-ethanamine and Acute-Disease

Endothelial dysfunction is an early event in the development of vascular complications in hyperhomocysteinemia. Endothelial cells release a number of vasodilators, including NO and prostacyclin. Several lines of evidence have indicated the existence of a third vasodilator pathway, mediated by endothelium-derived hyperpolarizing factor (EDHF). EDHF is a major determinant of vascular tone in small resistance vessels. The influence of hyperhomocysteinemia on EDHF is unknown. The present in vivo study evaluates the integrity of the EDHF pathway in the renal microcirculation of rats with acute and chronic hyperhomocysteinemia.. EDHF-mediated vasodilation was evaluated as the renal blood flow (RBF) response to intrarenal acetylcholine during systemic NO synthase and cyclooxygenase inhibition. Acute hyperhomocysteinemia induced by intravenous homocysteine did not affect EDHF-mediated vasodilation. In contrast, intravenous methionine with subsequent hyperhomocysteinemia impaired the EDHF-mediated RBF response. When the methionine infusion was preceded by adenosine periodate oxidized to prevent the cleavage of S-adenosylhomocysteine to homocysteine and adenosine, a similar impairment of EDHF was observed, but with normal homocysteine levels. Animals with chronic hyperhomocysteinemia induced by a high-methionine, low-B vitamin diet during 8 weeks had a severely depressed EDHF-mediated vasodilation compared with those on a standard diet. Endothelium-independent vasodilation to deta-NONOate and pinacidil was not affected in acute and chronic hyperhomocysteinemia, demonstrating intact vascular smooth muscle reactivity.. EDHF-dependent responses are impaired in the kidney of hyperhomocysteinemic rats. Because EDHF is a major regulator of vascular function in small vessels, these findings have important implications for the development of microangiopathy in hyperhomocysteinemia.

Topics: Acetylcholine; Acute Disease; Adenosine; Animals; Biological Factors; Chronic Disease; Cyclooxygenase Inhibitors; Endothelium, Vascular; Female; Hyperhomocysteinemia; Indomethacin; Methionine; Muscle, Smooth, Vascular; NG-Nitroarginine Methyl Ester; Nitric Oxide Donors; Nitroso Compounds; Oxidation-Reduction; Pinacidil; Potassium Channels; Rats; Rats, Wistar; Renal Circulation; Vasodilation; Vitamin B Complex; Vitamin B Deficiency

Endogenous and exogenous nitric oxide (NO) may have important antibacterial effects in patients with pneumonia. NO administration has been limited to the continuous inhalation of gas-phase NO (ie, inhaled NO [iNO]). Intermittent nebulization of NONOates, novel NO donors, may permit the continuous intrapulmonary delivery of NO. Thus, we assessed the effects of nebulized diethylenetetraamine-NONOate (DETA-NO) in a model of acute Pseudomonas aeruginosa pneumonia.. Randomized, controlled study.. Male C57Bl/6 mice.. Pneumonia was induced by intratracheal instillation of P aeruginosa (3 x 10(7) CFU in 50 microL). Pneumonia and sham mice were randomized to receive no treatment, nebulized DETA-NO (12.5 or 125 micromol) at 4 h and 12 h, or continuous iNO for 24 h (10 or 40 ppm) until they were killed at 24 h.. The nebulization of DETA-NO was associated with a marked increase in mean (+/- SEM) exhaled NO levels (after nebulization, 484 +/- 34 parts per billion [ppb]; baseline, 13.4 +/- 0.4 ppb; p < 0.01) and plasma levels of nitrites/nitrates (after nebulization, 73 +/- 28 microM; at baseline, 14 +/- 3 microM; p < 0.05). Nebulized DETA-NO decreased the pulmonary bacterial load in mice with pneumonia by 65 +/- 19% (p < 0.05 vs untreated mice) but had no effect on pulmonary leukocyte infiltration. Although the growth of P aeruginosa colonies in vitro was impaired on exposure to DETA-NO, growth was similarly impaired by exposure to DETA nucleophile/backbone alone.. The nebulization of DETA-NO provides a method for the prolonged intrapulmonary delivery of NO. The antibacterial effect of DETA-NO in vivo and in vitro is due, in large part, to the DETA nucleophile moiety and is independent of NO, suggesting a limited therapeutic role for exogenous NO in pneumonia.

Topics: Acute Disease; Aerosols; Animals; Disease Models, Animal; Hydrazines; Lung; Male; Mice; Mice, Inbred C57BL; Nitrates; Nitric Oxide; Nitrites; Nitroso Compounds; Pneumonia, Bacterial; Pseudomonas aeruginosa; Pseudomonas Infections; Random Allocation

Nitric oxide (NO) inhibits growth and induces differentiation in acute myeloid leukaemia (AML) cells. To identify genes associated with these processes, we studied the effect of NO on AML gene expression using the technique of Representational Difference Analysis. Exposure of HL-60 cells to the NO donor DETA-NO for 24 h induced the expression of a novel gene that was named rno (regulated by nitric oxide). Treatment of HL-60 cells with dimethyl sulphoxide induced expression of rno, but treatment with Vitamin D3 or all-trans retinoic acid did not. Upregulation of rno by NO was cGMP independent. Northern blot analysis indicated that constitutive expression of the novel gene was limited to leucocytes. Three isoforms of rno were identified. An rno cDNA clone was obtained by screening a human leucocyte library. The nucleotide sequence of the open reading frame shared significant homology with that of the human ribonuclease/angiogenin inhibitor (RI). The predicted amino acid sequence indicated that, like RI, rno is leucine and cysteine rich and is comprised of a series of repetitive elements (leucine-rich repeats) that may mediate macromolecular interactions. Enhancement of expression of rno may be a component of the process by which differentiation and growth inhibition of leukaemia cells is induced by NO.

Topics: 8-Bromo Cyclic Adenosine Monophosphate; Acute Disease; Amino Acid Sequence; Base Sequence; Blotting, Northern; Enzyme Inhibitors; Gene Expression Regulation; Guanylate Cyclase; HL-60 Cells; Humans; Leukemia, Myeloid; Leukocytes; Molecular Sequence Data; Nitric Oxide Donors; Protein Isoforms; Proteins; Repetitive Sequences, Amino Acid; Reverse Transcriptase Polymerase Chain Reaction; Ribonuclease, Pancreatic; Sequence Homology, Nucleic Acid; Sulfuric Acid Esters; Triazenes