In the perfused rabbit lungs, PMA application induced a vasoconstrictor response
In the perfused rabbit lungs, PMA application induced a vasoconstrictor response, which was also largely attenuated in the presence of SOD as well as in the presence of apocynin (table 1). To investigate the effect of inspired oxygen concentration on the PMA-induced increment in CP?formation, we performed short-term ventilation periods of 30 min at varying O2 concentrations, followed by bolus application of PMA (1 ) into the pulmonary artery. The increases in the ESR signal intensity/min post-PMA was compared to that pre-PMA application (Fig. 6A). The highest increase in ESR signal intensity/time was observed when the lungs were ventilated with 5 O2, within a total range of 1 ?21 O2. Parallel experiments in the presence of SOD, revealed that the major portion of the increase in the ESR signal was due to superoxide release. Again, replacement of the lungs by a fiber oxygenator, to equilibrate the buffer fluid with the different oxygen concentrations did not change the increase rate in ESR signal intensity after PMA application, either in the absence or in the presence of 1 FeCl2 (Fig. 6A). PMA application induced an increase in PAP (Fig. 6B). This increase was highest when lungs were ventilated with 5 O2.DiscussionMethodological aspects Because ROS formation has been implicated in a variety of lung diseases, the detection of ROS release from the pulmonary circulation is thought to be important [7-9]. However, current methods for the detection of lung vascular ROS formation lack specificity due to autoxidation of the substrates employed, the lack reliability due to artificial ROS generation by redox cycling [22,24,25], and a lack sensitivity of the techniques employed. The ESR technology may overcome several of these shortfalls. In a previous study, Katz and colleagues used spin trapping and ESR technology for ROS detection in isolated perfused rabbit lungs. However, in that investigation, the spinPage PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/27488460 4 of(page number not for citation purposes)Respiratory Research 2005, 6:http://respiratory-research.com/content/6/1/A)B)signal intensity (AU)120 100 80 60 40 20 0? 2mM DFO (n=4) 2mM DFO (n=4)– DFO (n=8) DFO (n=8) ? 20 DFO (n=5) DFO (n=8) (n=5) DFO (n=8) ?20 DFO (n=5) 2mM DFO (n=5) (n=4) 20 DFO (n=4)–* * * * *******time (h)The effect of the iron chelating agent deferoxamine (DFO) on CP?nitroxide signal intensity in vitro Figure 1 The effect of the iron chelating agent deferoxamine (DFO) on CP?nitroxide signal intensity in vitro. (A) Typical ESR spectrum of CP?nitroxide resulting from the reaction of the hydroxylamine spin probe CPH with ROS. The height of the first field component of the triple-line spectrum was used for AM152 site quantification of signal intensity. (B) In-vitro incubation of CPH (1 mM) in Krebs-Henseleit buffer. Signal intensity is given in arbitrary units (AU). Data are shown for CPH oxidation in the absence (-DFO) or in the presence of either 20 or 2 mM deferoxamine (DFO). Asterisks indicate significant differences when compared to the-DFO group.Page 5 of(page number not for citation purposes)Respiratory Research 2005, 6:http://respiratory-research.com/content/6/1/900FeCl H2O2 Fe(II)2// H2O2 (n=4)(n=4)p < 0.control (n=4) control (no Fe(II) / H2O2) (n=4)signal intensity (AU)700 600 500 400 300 200 100 0 0 0.5 1 1.5 2 2.5 FeCl2 H2Otime (h)Figure H2O2 The ESR2signal intensity in isolated perfused and ventilatedrabbit lungs during baseline conditions and in the presence of FeCl2/ The ESR signal intensity in isolated.
