Biomedical Engineering Reference
In-Depth Information
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ACH
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Time (minutes)
FIGURE 1.10
Laser-doppler fl owmetry (a) and NO measurement (b) from one subject. Upon heating
the subject to 39ºC, at
10 min, NO production and skin blood fl ow increased, which instantly returned to
normal upon cooling the subject at
45 min. After heat stress and cooling, ACh was administered by intra-
dermal microdialysis to confi rm the ability of the microelectrode to measure NO concentrations. (Reprinted
with permission from the American Physiological Society [125].)
WPI was inserted into the cutaneous interstitial space of the forearm of nine human
patients to measure NO concentration while the subjects were at low (34ºC) and high
(39ºC) temperature. Laser-Doppler fl owmetry (LDF) was used to monitor skin blood fl ow
(SkBF) [125]. This publication demonstrated that NO concentration, as well as SkBF
increased in the cutaneous interstitial space during heat stress in humans. Figure 1.10
shows the key results for these experiments. As the temperature is increased at
10 min
the data show that the blood fl ow (top plot) and NO concentration (bottom plot) increased
as a function of temperature. Also, as the temperature was decreased again, at
45 min,
the blood fl ow and NO concentration returned to its original value. At
130 min, while
the subjects were at low temperature, the investigators injected acetylcholine to show that
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