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the NO concentrations taken pre and post the water experiment (p=0.095). There was
difference in the COz or duration of expiration across the three sets of exhalations made.
Figure 7.9: The etfect of consuming water on the subsequent exhaled NO levels measured
.o 2fi
e
Eo 't
a lso
o = 100
E Ps0
x
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Comparison of peak exhaled NO levels with the exhalation performed in a standard manner pre and
post a set of exhalations done where the consumption of either hot (in red) or cold (in black) took
place just prior to each exhalation. Each point is a mean of five exhalations.
7.7 Discussion: which measurement factors alter nitric oxide levels?
The methodological experiments described in Chapter 6 and 7 demonstrated that the
measurement of NO in exhaled air was feasible. A number of cross-sectional studies looking
at exhaled NO concentrations in different subject groups had been reported. The findings
within each research team had been consistent, but the absolute levels of NO reported by the
investigators in similar subject $oups were very different. All these investigators used NO
chemiluminescence analysers which, although developed by different companies, had similar
sensitivities and they stated that regular calibration was being performed. The study groups
were similar. For example, the results in healthy control subjects through the 1990s were
reported with means of 3.25ppb, 4.7Sppb and 100.25ppb under different conditions @ersson,
Wiklund et al. 1993), 4.7ppb (Massaro, Mehta et al. 1996),6.2ppb (Massaro, Gaston et al.
1995), 8.lppb (Borland, Cox et al. 1993), 8.4ppb @ersson, Zetterstrom et al. 1994), 8.6ppb
(Trolin, Anden et al. 1994), 9ppb (Alving, Weitzberg et al. 1993), 11.lppb (Martin, Bryden et
al. 1996), l6ppb (Schedin, Frostell et al. 1995), l9ppb and 2lppb (Schilling, Holzer et al.
1994),22ppb (Kimberly, Nejadnik et al. 1996), 26.3ppb (Iwamoto, Pendergast et al. 1994),
34ppb (Jilma, Kastner et al. 1996),42ppb (Gerlach, Rossaint et al. 1994), 51 NO g-r 6Morris,
Sooranna et al. 1996), 70ppb and 75ppb (Kharitonov, Logan-Sinclair et al. 1994), 80.2ppb
(Kharitonov, Yates et al. 1994), 88ppb (Kharitonov, Robbins et al. 1995), 89ppb (Kharitonov,
Wells et al. 1995) and l05.5ppb (Robbins, Floreani et al. 1996). Similar ranges in NO results
t70