The Vasodilatory Response of Skin Microcirculation to Local Heating is Subject to Desensitization

Abstract

Background. ln humans, local heating increases skin perfusion by mechanisms dependent on nitric oxide (NO). Because the vascular effects of NO may be subject to desensitization, we examined whether a first local thermal stimulus would attenuate the hyperemic response to a second one applied later.

In vivo reflectance-mode confocal microscopy provides insights in human skin microcirculation and histomorphology

“…Our results evaluated in vivo by RCM are in agreement with previous studies on temperature induced alterations in human skin microcirculation [11][12][13][14]. Recently, Ciplak et al studied the vasodilatory response of skin microcirculation to local heating using laser Doppler imaging [12].…”

“…Recently, Ciplak et al studied the vasodilatory response of skin microcirculation to local heating using laser Doppler imaging [12]. Using non-invasive near infrared spectrometer, Gomez et al examined the dynamic tissue oxygen saturation [3].…”

“…For correlation, confocal images were compared to histological sectioning and a high sensitivity of 82.9% and specificity of 95.7% was found [9,10]. The dynamic effects of temperature changes on the human skin microcirculation are well investigated using non-invasive approaches and also well described in the actual literature [11][12][13][14][15][16]. Temperature-dependent microcirculation changes have been studied, but only at temperatures that damage the skin, using more complex techniques such as fluorescence [17].…”

Axon reflex-related hyperemia induced by short local heating is reproducible

“…Therefore, when testing a random recording site, heating for longer than 30 min to gain peak cutaneous vascular conductance (CVC) from the plateau or maximal dilatation phase is needed to normalize the initial peak CVC as a percentage of the plateau peak or percentage of the maximum for comparison (Minson et al, 2001;Roustit et al, 2010a,b;Tew et al, 2011). The initial peak is enhanced and the plateau peak is inhibited in the second test at a 2 h interval (Ciplak et al, 2009;Frantz et al, 2012). Additionally, the test usually takes longer than 1-1.5 h. Therefore, a test-retest at the same recording site is not feasible within a short period of time, and different recording sites must be used in the same subject when this long heating protocol is used to evaluate the effects of interventions (Carter Microvascular Research 84 (2012) 351-355 andHodges, 2011;Caselli et al, 2003;Hodges et al, 2008Hodges et al, , 2009Houghton et al, 2006;Kellogg et al, 1999Kellogg et al, , 2009Shastry and Joyner, 2002).…”

“…We hypothesized that fixing the recording site in the same session could provide acceptable reproducibility through controlling the variations of both capillary densities and sensory innervations. Because AR flare can be induced within 5 min of heating, which is relatively time-saving and may minimize the order effect between two tests (Ciplak et al, 2009;Frantz et al, 2012), a short-heating protocol can be used to investigate the effect of an acute intervention or short treatment on the AR flare response at the same recording site for a testretest during the same session. The present study proposed a modified protocol by shortening the heating period to specifically assess the AR flare response and fixing the recording site to reduce both the variability of capillary density and sensory innervation.…”