• Neurochemical research · May 1998

    Use of a hemoglobin-trapping approach in the determination of nitric oxide in in vitro and in vivo systems.

    • A Balcioglu, C J Watkins, and T J Maher.
    • Massachusetts Institute of Technology, Department of Brain and Cognitive Sciences, Cambridge 02139, USA.
    • Neurochem. Res. 1998 May 1;23(5):815-20.

    AbstractWe describe methods for measuring the release of nitric oxide (NO) derived from organic nitrates in vitro, using triple wavelength and difference spectrophotometry in the presence and absence of concentric microdialysis probes. These methods are based on the ability of NO to oxidize oxyhemoglobin (OxyHb) to methemoglobin (MetHb) quantitatively in aqueous solution. Isosorbide dinitrate (ISDN), a thiol-dependent organic nitrate, increased MetHb concentration in 45 min from 2.47 +/- 0.47 to 4.15 +/- 0.12 microM (p < 0.05) and decreased OxyHb concentration from 2.13 +/- 0.35 to 0.33 +/- 0.26 microM (p < 0.05) at 37 degrees C. At 27 degrees C, the OxyHb concentration was not significantly altered (2.04 +/- 0.23 to 1.60 +/- 0.04 microM) by ISDN, nor was the MetHb concentration (from 2.68 +/- 0.50 to 2.59 +/- 0.25 microM). Sodium nitroprusside (SNP), a thiol-independent organic nitrate, increased MetHb concentrations in 30 min from 4.21 +/- 0.26 to 6.00 +/- 0.56 microM (p < 0.05) at 37 degrees C, and from 4.23 +/- 0.39 to 5.90 +/- 0.43 microM (p < 0.01) at 27 degrees C. SNP also decreased OxyHb concentrations in 30 min from 1.99 +/- 0.32 to 0.13 +/- 0.12 microM (p < 0.01) at 37 degrees C, and from 2.25 +/- 0.31 to 0.13 +/- 0.09 microM (p < 0.01) at 27 degrees C. Difference spectrophometry indicated that 0.25-5 mM SNP significantly increased NO production in a dose-dependent fashion. This hemoglobin-trapping technique was also useful in quantifying the concentrations of NO released from SNP in aqueous solution in vitro, using concentric microdialysis probes. The NO concentration following exposure to SNP was 530 +/- 50 nM, as determined using the difference spectrophotometric technique. To demonstrate the applicability of this technique to in vivo microdialysis, we implanted concentric microdialysis probes into hippocampus and cerebellum of conscious and anesthetized rats. Baseline NO concentrations in hippocampus of conscious and anesthetized rats were 11 +/- 2 nM and 23 +/- 9 nM, respectively, while in the cerebellum NO concentrations were 28 +/- 9 nM and 41 +/- 20 nM, respectively. These results demonstrate that microdialysis using a novel hemoglobin-trapping technique possesses adequate sensitivity to measure the NO levels produced from organic nitrates in aqueous solutions, and further document the applicability of this approach to in vivo systems.

      Pubmed     Copy Citation     Plaintext  

      Add institutional full text...

    Notes

     
    Knowledge, pearl, summary or comment to share?
    300 characters remaining
    help        
    You can also include formatting, links, images and footnotes in your notes
    • Simple formatting can be added to notes, such as *italics*, _underline_ or **bold**.
    • Superscript can be denoted by <sup>text</sup> and subscript <sub>text</sub>.
    • Numbered or bulleted lists can be created using either numbered lines 1. 2. 3., hyphens - or asterisks *.
    • Links can be included with: [my link to pubmed](http://pubmed.com)
    • Images can be included with: ![alt text](https://bestmedicaljournal.com/study_graph.jpg "Image Title Text")
    • For footnotes use [^1](This is a footnote.) inline.
    • Or use an inline reference [^1] to refer to a longer footnote elseweher in the document [^1]: This is a long footnote..

    hide…