Regulation Of Skin Blood Flow Research Articles

Skin temperature response to thermal stimulus in patients with hyperhidrosis: A comparative study

Primary hyperhidrosis (HH), the excessive sweating exceeding physiological demand, has been associated to a complex dysfunction of the autonomic nervous system which may explain the disfunction in sweating but may also cause unrevealed alterations in skin blood flow regulation. In fact, HH patients present a sympathetic over-function with less reflex bradycardia in response to the Valsalva maneuver and higher sympathetic skin responses. We aimed to identify response patterns to room thermal stimulus in HH patients compared to a control group in order to investigate putative differences in blood flow assuming that skin temperature in glabrous (non-hairy) areas reflect the sympathetic tone in arteriovenous anastomoses (AVAs). Infrared thermography images were obtained from a cohort of patients diagnosed with HH, followed at a hospital pediatric surgical department and to a sex- and age-matched control group of patients admitted for other surgical procedures. With the participants in Fowler's position, a set of 3 images were captured simultaneously and 44 regions of interest were analyzed, distributed on the palms of the hands, soles of the feet, axilla, and inner canthus. After an acclimatization period at 20 °C, the room temperature was increased to 24, 28 and 32 °C to obtain similar sets of thermograms. A total of 37 patients with HH and 16 participants in the control group were included in the study. At baseline (20 °C), body core temperature (measured in the inner canthus) was significantly higher in the HH patients compared to the controls (p = 0.019 and p = 0.003 in right and left inner canthi, respectively), without any significant differences in the other thermograms. When room temperature was increased, differences in core temperature disappeared, while differences appeared in axilla and palms of the hands with HH patients presenting significantly lower temperature at the three thermal stimulus stages. Patients with HH presented a lower thermoregulatory response when submitted to room temperature increase, which may reflect a vasomotor sympathetic over-function in AVAs.

Skin Microhemodynamics and Mechanisms of Its Regulation in Type 2 Diabetes Mellitus.

The review presents modern ideas about peripheral microhemodynamics, approaches to the ana-lysis of skin blood flow oscillations and their diagnostic significance. Disorders of skin microhemodynamics in type 2 diabetes mellitus (DM) and the possibility of their interpretation from the standpoint of external and internal interactions between systems of skin blood flow regulation, based on a comparison of couplings in normal and pathological conditions, including models of pathologies on animals, are considered. The factors and mechanisms of vasomotor regulation, among them receptors and signaling events in endothelial and smooth muscle cells considered as models of microvessels are discussed. Attention was drawn to the disturbance of Ca2+-dependent regulation of coupling between vascular cells and NO-dependent regulation of vasodilation in diabetes mellitus. The main mechanisms of insulin resistance in type 2 DM are considered to be a defect in the number of insulin receptors and impaired signal transduction from the receptor to phosphatidylinositol-3-kinase and downstream targets. Reactive oxygen species plays an important role in vascular dysfunction in hyperglycemia. It is assumed that the considered molecular and cellular mechanisms of microhemodynamics regulation are involved in the formation of skin blood flow oscillations. Parameters of skin blood microcirculation can be used as diagnostic and prognostic markers for assessing the state of the body.

Spectral analysis of blood flow oscillations to assess the plantar skin blood flow regulation in response to preconditioning local vibrations.

Local vibration has shown promise in improving skin blood flow and wound healing. However, the underlying mechanism of local vibration as a preconditioning intervention to alter plantar skin blood flow after walking is unclear. The objective was to use wavelet analysis of skin blood flow oscillations to investigate the effect of preconditioning local vibration on plantar tissues after walking. A double-blind, repeated measures design was tested in 10 healthy participants. The protocol included 10-min baseline, 10-min local vibrations (100 Hz or sham), 10-min walking, and 10-min recovery periods. Skin blood flow was measured over the first metatarsal head of the right foot during the baseline and recovery periods. Wavelet amplitudes after walking were expressed as the ratio of the wavelet amplitude before walking. The results showed the significant difference in the metabolic (vibration 10.06 ±1.97, sham 5.78 ±1.53, p <0.01) and neurogenic (vibration 7.45 ±1.54, sham 4.78 ±1.22, p <0.01) controls. There were no significant differences in the myogenic, respiratory and cardiac controls between the preconditioning local vibration and sham conditions. Our results showed that preconditioning local vibration altered the normalization rates of plantar skin blood flow after walking by stimulating the metabolic and neurogenic controls.

The cardiovascular response to ambient temperature changes within the human thermoneutral zone

IntroductionThe human temperature control within the thermoneutral zone (TNZ) depends on the regulation of skin blood flow to hands and feet (acral skin) [1]. The acral skin blood flow is regulated by absolute level and fluctuations in arterio‐venous anastomoses’ vasculature resistance. We hypothesized that a change in ambient temperature would not affect the hemodynamic responses within the TNZ in healthy humans.MethodsTwenty‐four young healthy human subjects were exposed to three ambient temperatures (20°C, 26°C and 32°C) while supine and lightly dressed in a climate chamber. Each temperature plateau lasted for 40 minutes. The protocol either started at 20°C or 32°C, with a subsequent increase or decrease in temperature, respectively, and the order was randomized. Beat‐by‐beat blood flux from both index fingers and the left forearm were recorded simultaneously by laser Doppler flowmetry (DRT4, Moor Instruments, Devon, UK), together with heart rate (HR, from ECG). Non‐invasive finger arterial blood pressure (Finometer, Finapres Medical System, Netherlands; calibrated at each temperature plateau) was recorded continuously from the right middle finger, providing mean arterial pressure (MAP) and estimated beat‐to‐beat cardiac stroke volume (SV). The medians and their corresponding 95% confidence intervals were calculated by Hodges‐Lehmann’s estimates. Wilcoxon signed rank sum test for paired samples tested differences between states.Preliminary resultsIncreasing ambient temperature from 20°C to 32°C caused a five‐fold increase in left fingertip flux (p&lt;0.003) while left forearm flux doubled (p&lt;0.008). The fluctuations in the bilateral fingertip flux were maximum correlated at 26°C (&gt;0.82) and significantly higher than the correlation at 32°C (0.73, p&lt;0.01 as compared to 26°C). The hemodynamic variables changed significantly within the TNZ. MAP decreased from 74 (70,77) mmHg at 20°C to 64 (60,68) mmHg at 32°C (p&lt;0.0001). SV decreased from 102 (93, 113) ml at 20°C to 97 (86, 106) ml at 32°C (p&lt;0.0004). HR increased minimally from 20°C (56 bpm (52, 59) to 32°C (58 bpm (56, 61) (p=0.01).ConclusionsThe marked changes in acral skin blood flow within TNZ affected the central hemodynamic variables, with the vasodilation reflected in MAP decrease coinciding with an increase in ambient temperature. HR and SV showed minimal changes within TNZ.Support or Funding InformationThe Research Council of Norway (grant no: 230354)

A new approach to the analysis of skin blood flow oscillations in human

It is considered that there are six non-overlapping frequency intervals with constant boundaries. These intervals correspond to different mechanisms of skin blood flow regulation. The boundaries do not depend on functional conditions but this statement should be verified. Also it remains unclear how the oscillatory components of skin blood flow are related. Thus the study is aimed to verify statistically the boundaries of frequency intervals, to test the hypothesis that the boundaries depend on age and to search for relationships between spectral components of skin blood flow. The study involved 105 healthy volunteers aged from 20 to 65 years, which were divided into two age groups. Skin blood flow was registered with laser Doppler flowmeter (LDF). Assessments of frequency interval boundaries and relationship between the frequency oscillatory components of blood flow were conducted with histogram approach, bootstrap method and correlation analysis. New frequency interval boundaries were found. They were different in two groups. A linear correlation and frequency areas with moderate (0.5–0.7) and high (>0.7) correlation coefficients were found between spectral components of blood flow. The dependence of these correlations on the age was shown. Thus we proposed a conceptually new approach to analysis of spectral components of skin microhemodynamics and interpretation of results obtained by laser Doppler techniques. This approach is the result of the development of modern understanding of relationships between skin blood flow regulation mechanisms and spectral components of LDF signals. It allows one to have a new look at these relationships as well as demonstrates their dependence on the functional state of the organism as a whole.

Relationship between skin blood flow regulation mechanisms and vascular endothelial growth factor in patients with metabolic syndrome.

The focus of this paper is the determination of endothelial dysfunction in patients with metabolic syndrome (MetS) and the establishment of a relationship between the traditional biomarkers of endothelial dysfunction and the vascular tone regulation indices obtained from indirect cold tests in MetS patients. Our investigation was conducted on 30 patients aged 45.5±9 years. The control group comprised 14 healthy subjects aged 48.2±2.4 years. The mechanism of vascular tone regulation was investigated using the wavelet analysis of skin temperature oscillations (WAST). The degrees of microvascular vasoconstriction and vasodilatation were determined during contralateral cold tests in the endothelial (0.02-0.0095 Hz), neurogenic (0.05-0.02 Hz) and myogenic (0.05-0.14 Hz) frequency ranges. In MetS patients, vasoconstriction indices were higher and vasodilatation indices were lower than in the subjects of the control group, which is indicative of disorders in the mechanisms of microvascular tone regulation. These indices correlate with the metabolic parameters and VEGF (vascular endothelial growth factor) levels. The correlation of vasoconstriction and vasodilatation indices with the main factors of the metabolic syndrome testifies that the biological and functional aspects of the endothelial dysfunction are closely related.

Asymmetrical responses of skin blood flow in ischemic hindlimbs to electrical stimulation of the unilateral forelimb

The regulation of skin blood flow (SBF) is primarily mediated by the sympathetic nervous system, but the effects of electrical stimulation (ES) of one limb on SBF in the other limbs remain unknown. The present study investigated the effects of unilateral forelimb ES on SBF in the bilateral hindlimbs in anesthetized rats. Bilateral hindlimb ischemia was induced by tourniquet application for 60min. After reperfusion for 24h, ES (3 or 125Hz) was applied to the upper one-fourth of the triceps brachii muscle of the left or right forelimb for 30min. Rats that did not receive ES were used as the controls. Bilateral hindlimb SBF was measured by a laser Doppler line scanner for 20min before ES, 30min during ES, and 9min after ES. The results showed significant differences in SBF in the right but not left hindlimb between the control group and experimental group that received 125-Hz ES of the right forelimb. Right hindlimb SBF significantly increased within 3min following the application of 125-Hz ES to the right forelimb. No significant changes in SBF were observed in the left or right hindlimb when 125-Hz ES was applied to the left forelimb. Moreover, 3-Hz ES of the left or right forelimb did not significantly change SBF in either hindlimb compared with the control group. These results indicate that unilateral forelimb ES causes a differential SBF response in the hindlimb via a specific somatosympathetic reflex, and ES-induced SBF improvements in the ischemic hindlimb are frequency-dependent.

Characterizing human skin blood flow regulation in response to different local skin temperature perturbations

Small nerve fibers regulate local skin blood flow in response to local thermal perturbations. Small nerve fiber function is difficult to assess with classical neurophysiological tests. In this study, a vasomotor response model in combination with a heating protocol was developed to quantitatively characterize the control mechanism of small nerve fibers in regulating skin blood flow in response to local thermal perturbation.The skin of healthy subjects' hand dorsum (n=8) was heated to 42°C with an infrared lamp, and then naturally cooled down. The distance between the lamp and the hand was set to three different levels in order to change the irradiation intensity on the skin and implement three different skin temperature rise rates (0.03°C/s, 0.02°C/s and 0.01°C/s). A laser Doppler imager (LDI) and a thermographic video camera recorded the temporal profile of the skin blood flow and the skin temperature, respectively.The relationship between the skin blood flow and the skin temperature was characterized by a vasomotor response model. The model fitted the skin blood flow response well with a variance accounted for (VAF) between 78% and 99%. The model parameters suggested a similar mechanism for the skin blood flow regulation with the thermal perturbations at 0.03°C/s and 0.02°C/s. But there was an accelerated skin vasoconstriction after a slow heating (0.01°C/s) (p-value<0.05). An attenuation of the skin vasodilation was also observed in four out of the seven subjects during the slow heating (0.01°C/s). Our method provides a promising way to quantitatively assess the function of small nerve fibers non-invasively and non-contact.

Active skin perfusion and thermoregulatory response in the hand following nerve injury and repair in human upper extremities

Cutaneous vasoconstriction/vasodilatation occurs in response to whole body and local cooling/heating, and the vasomotor activities play a pivotal role in thermal control of the human body. The mechanisms underlying regulation of skin blood flow involve both neurogenic and humeral/local chemical influence, contributing to the initial response to thermal stimuli and the prolonged phase of response, respectively. Previous studies have suggested the impairment of cutaneous thermal regulation after nerve injury. However, the evidence regarding how the skin perfusion and thermoregulatory response evolve after nerve injury and repair remains limited. Here we observed, by utilizing laser-Doppler perfusion imaging, baseline skin perfusion and perfusion change in response to thermal stimuli after median and ulnar nerve injury, and the results showed that baseline perfusion in autonomous skin area profoundly decreased and active rewarming after clod stress dramatically diminished before sensory recovery of the skin became detectable. In addition, baseline cutaneous perfusion was recovered as the skin regained touch sensation, and exhibited positive correlation to touch sensibility of the skin. These data indicate that both active perfusion and thermoregulatory response of the skin are markedly compromised during skin denervation and can be recovered by re-innervation. This suggests the importance of timely repair of injured nerve, especially in the practice of replantation.

Nitric oxide in the nucleus raphe magnus modulates cutaneous blood flow in rats during hypothermia.

Nucleus Raphe Magnus (NRM) that is involved in the regulation of body temperature contains nitric oxide (NO) synthase. Considering the effect of NO on skin blood flow control, in this study, we assessed its thermoregulatory role within the raphe magnus. To this end, tail blood flow of male Wistar rats was measured by laser doppler following the induction of hypothermia. Intra-NRM injection of SNP (exogenous NO donor, 0.1- 0.2 μl, 0.2 nM) increased the blood flow. Similarly, unilateral microinjection of glutamate (0.1- 0.2 μl, 2.3 nM) into the nucleus increased the blood flow. This effect of L-glutamate was reduced by prior intra NRM administration of NO synthase inhibitor N(G)-methyl-L-arginine or N(G)-nitro-L-arginine methyl ester (L-NAME, 0.1 µl, 100 nM). It is concluded that NO modulates the thermoregulatory response of NRM to hypothermia and may interact with excitatory amino acids in central skin blood flow regulation.

Blood flow dynamics and sensitivity in breasts after reconstruction with DIEP-flap

A method of breast reconstruction is based on the Deep Inferior Epigastric Perforator (DIEP) technique. Skin and fat are transplanted from the abdomen to the chest; blood vessels are reconnected through microsurgery. Nerves are, however, left unconnected. This study aims to evaluate the blood flow and reinnervation of blood vessels and skin in breasts reconstructed by DIEP flaps without neural repair. In all, DIEP flaps of 10 patients were tested at an average of 16.3 months postoperatively. Blood flow was assessed by PeriScan PIM II System, both before and after indirect heating. Tactile perception threshold was assessed by Semmes-Weinstein monofilament and thermal sensibility by SENSELab MSA Thermotest. The patients' contralateral breasts were used as controls. The blood flow of the flaps was statistically significantly lower than in the control breasts, both before and after indirect heating. The change in blood flow after indirect heating did, however, not significantly differ when comparing the breasts. All flaps regained deep pressure sensibility in all four quadrants. Five patients regained even better sensibility in one of their quadrants. Seven patients regained perception of cold stimuli, five perceived warmth. This study has shown that skin blood flow regulation is present in DIEP flaps 1 year after reconstruction. Blood flow dynamics are very similar to those in the normal breast. There is also a recovery of tactile and thermal sensibility, but this study has not shown any clear parallels between recovery blood flow, tactile sensibility and thermal sensibility.

Sodium loading and cutaneous microvascular function: more than skin deep

For several years the human cutaneous circulation has been utilized as a representative vascular bed to assess microvascular function in clinical and pre-disease model populations. With relevance to hypertension, deficits in cutaneous microvascular function are related to impairment in indices of renal vascular function and target organ damage (Coulon et al. 2011). While the skin serves mainly thermoregulatory purposes, several skin-specific methodologies including both thermal and pharmacological stimuli and interventions have been successfully utilized to pharmacodissect underlying mechanisms of vascular dysfunction (Holowatz et al. 2008). The most commonly explored signalling pathways in human skin most relevant to globalized vascular dysfunction are nitric oxide synthase (NOS)-dependent vasodilatory mechanisms, and noradrenaline-mediated vasoconstrictor mechanisms. Moreover, specific pathology-relevant oxidant stress mechanisms have been explored using both specific and non-specific antioxidants including allopurinol, apocynin and ascorbate (Medow et al. 2011). In this issue of The Journal of Physiology, Greaney et al. (2012) published an elegant study examining the effects of dietary sodium loading on microvascular function, independent of an increase in blood pressure. This study is the first to show that dietary sodium loading in normotensive salt-resistant humans impairs cutaneous eNOS-dependent vasodilatation utilizing a local skin heating stimulus. Furthermore, when the non-specific antioxidant ascorbate was locally delivered, eNOS-dependent vasodilatation was restored. Together, the data from Greaney et al. show that dietary sodium-induces decrements in cutaneous microvascular function that occur through ascorbate-sensitive oxidant stress mechanisms. The results from this study bring to light several interesting points to consider from both a globalized vascular health perspective and for methodological reasons when examining the neurovascular regulation of skin blood flow. Human skin has been used as a model for examining decrements in vascular function with hypertension-induced vascular pathology for several decades. While as a regional circulation the compliant cutaneous circulation contributes minimally to the increase in systemic vascular resistance in comparison to more nutritive vascular beds, decrements in microvascular function are clearly apparent. Even before the technology was available to image or measure more precise changes in microcirculatory function through laser-Doppler or laser-speckle imagery, Carberry et al. (1992) utilized venous occlusion plethysmography and a whole limb heating technique to show that subjects with essential hypertension have lower forearm blood flows to increasing temperature and lower maximal blood flow, indicating a degree of endothelial dysfunction and inward vessel remodelling. Moreover, progressive decrements in vascular function to endothelium-dependent agonists with the severity of hypertensive disease have been consistently observed (Farkas et al. 2004). More recently with the development of skin-specific methodologies the underlying mechanisms of hypertension-induced vascular dysfunction are being extensively explored (Smith et al. 2011). The study by Greaney et al. adds another piece to the puzzle suggesting that dietary salt loading alone without increases in mean arterial pressure induces changes in vascular function that are consistent with a pre-clinical hypertensive vascular pathology state. From a methodological perspective, the results from Greaney et al. highlight the need for cautious experimental controls in all studies examining the neurovascular regulation of skin blood flow whether in healthy or clinical populations. Controlling or documenting sodium intake in human subjects may be a necessary experimental control especially when examining clinical populations. Finally, meaningful physiological interpretations of studies like that of Greaney et al. are not possible without tightly controlled mechanistic work in healthy populations. More of this work is necessary so that clinical test of microvascular function in the skin can be utilized on a broader scale (Minson, 2010).

The Method of In-Vivo Electrical Field Stimulation to Study Neurogenic Control of Skin Blood Flow

Skin blood flow (SkBF) plays a vital role in regulating body temperature but the mechanisms regulating it remain poorly understood. Current methods used to study these mechanisms may activate both local and systemic factors which may limit our ability to differentiate the role of various neurochemicals involved in the regulation of SkBF. PURPOSE: To characterize a novel method of in-vivo electrical field stimulation (I-EFS) to study neurogenic control of cutaneous vasodilation in the absence of the sympathetic adrenergic nervous system. METHODS: Three intradermal microdialysis probes were placed in the skin of the dorsal side of the forearm of 6 men and 3 women. The adrenergic nervous system was eliminated by delivery of a cocktail of phentolamine (0.01 mg/ml), propranolol (1 mM), and BIBP-3226 (10 μM). At one skin site, atropine (0.1 mg/ml) was added to also block acetylcholine receptors (RACh). At a second site L-NAME (10 mM) and atropine (0.1 mg/ml) blocked nitric oxide synthase (NOS) and RACh. Finally at a third site, RACh, NOS, and vasoactive intestinal peptide receptors (RVIP, 0.47 mg/ml VIP10-28) were blocked. The SkBF response to 1 minute stages of graded increases in frequency (0.2, 1, 2, 4, 8, and 32 Hz) at a current of 1.0 ± 0.1 mA was used to generate a stimulus-response curve before and after drug delivery. RESULTS: I-EFS in the presence of adrenergic blockade produced a frequency dependent increase in SkBF with area under the SkBF-time curve (AUC) averaging 614 ± 279% SkBFmax·min. RACh blockade had minimal impact on AUC which averaged 591 ± 331% SkBFmax·min (p>0.05). Combined NOS and RACh blockade appeared to lower the vasodilator response to I-EFS by 23% (1036 ± 457 to 801 ± 448% SkBFmax·min, p>0.05). Combined NOS, RACh, and RVIP blockade reduced the vasodilator response by 48% from 802 ± 412 to 418 ± 268% SkBFmax·min (p=0.07). CONCLUSION: RACh blockade had no effect on the vasodilation induced by I-EFS in the presence of adrenergic blockade, while NOS and RVIP blockade appeared to attenuate the vasodilator response to I-EFS. I-EFS may be an effective method to determine the role of various local neurochemicals on skin blood flow.

About “Chronic low-dose aspirin therapy attenuates reflex cutaneous vasodilatation in middle-aged humans”

LETTERS TO THE EDITORAbout “Chronic low-dose aspirin therapy attenuates reflex cutaneous vasodilatation in middle-aged humans”G. Mahe, P. Rousseau, J. L. Saumet, and P. AbrahamG. Mahe, P. Rousseau, J. L. Saumet, and P. AbrahamPublished Online:01 Apr 2009https://doi.org/10.1152/japplphysiol.91653.2008MoreSectionsPDF (27 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInEmailWeChat to the editor: We read with much interest the article by Holowatz and Kenney (3) entitled “Chronic low-dose aspirin therapy attenuates reflex cutaneous vasodilatation in middle-aged humans.” The authors showed that chronic aspirin therapy (81 mg/day) plays a major role in the reflex cutaneous vasodilatation induced by whole body heating. This result is consistent with those reported by McCord et al. (4) that showed that the cyclooxygenase-dependent (COX) pathway was participating in the cutaneous vasodilatation induced by whole body heating but not by local heating. Vasodilatation induced by local heating relies on an axon-reflex for the early response and on a nitric oxide (NO)-dependent pathway for the late part of the response (5). On the contrary, vasodilatation induced by whole body heating depends on the NO pathway and the COX pathway but not on an axon-reflex (1, 3). The whole body heating is an interesting experimental model to study physiological responses during heat waves. Heat waves are an important health problem. Heat waves were estimated directly or indirectly to be responsible for ∼70,000 elderly deaths in Europe in 2003. Many elderly subjects take low-dose aspirin (<325 mg/day) as an effective therapy in prevention of cardiovascular diseases. As whole body heat-induced vasodilatation depends on the COX pathway even at low dose as shown by Holowatz and Kenney, do we need to stop low-dose aspirin therapy during heat waves? Other antiplatelet drugs exist (such as ADP inhibitors). We showed that the current-induced vasodilatation (CIV), another model of skin vasodilatation, was COX dependent(2) but not ADP dependent (6). Whether the whole body heating model is ADP dependent is an important issue. If not, rather than stop aspirin, should we recommend the use of antiplatelet drugs other than aspirin during heat waves? Future studies are likely needed to investigate this important clinical issue.REFERENCES1 Charkoudian N, Fromy B, Saumet JL. Reflex control of the cutaneous circulation after acute and chronic local capsaicin. J Appl Physiol 90: 1860–1864, 2001.Link | ISI | Google Scholar2 Durand S, Fromy B, Bouye P, Saumet JL, Abraham P. Vasodilatation in response to repeated anodal current application in the human skin relies on aspirin-sensitive mechanisms. J Physiol 540: 261–269, 2002.Crossref | PubMed | ISI | Google Scholar3 Holowatz LA, Kenney WL. Chronic low-dose aspirin therapy attenuates reflex cutaneous vasodilation in middle-aged humans. J Appl Physiol 106: 500–505, 2009.Link | ISI | Google Scholar4 McCord GR, Cracowski JL, Minson CT. Prostanoids contribute to cutaneous active vasodilation in humans. Am J Physiol Regul Integr Comp Physiol 291: R596–R602, 2006.Link | ISI | Google Scholar5 Minson CT, Berry LT, Joyner MJ. Nitric oxide and neurally mediated regulation of skin blood flow during local heating. J Appl Physiol 91: 1619–1626, 2001.Link | ISI | Google Scholar6 Rousseau P, Tartas M, Fromy B, Godon A, Custaud MA, Saumet JL, Abraham P. Platelet inhibition by low-dose aspirin but not by clopidogrel reduces the axon-reflex current-induced vasodilation in humans. Am J Physiol Regul Integr Comp Physiol 294: R1420–R1426, 2008.Link | ISI | Google ScholarAUTHOR NOTESAddress for reprint requests and other correspondence: G. Mahe, Univ. Hospital, 4, Rue Larrey, 49000 Angers, France (e-mail: [email protected]) Download PDF Previous Back to Top Next FiguresReferencesRelatedInformationCited ByReply to Mahe, Rousseau, Saumet, and AbrahamLacy A. Holowatz and W. Larry Kenney1 April 2009 | Journal of Applied Physiology, Vol. 106, No. 4 More from this issue > Volume 106Issue 4April 2009Pages 1471-1471 Copyright & PermissionsCopyright © 2009 the American Physiological Societyhttps://doi.org/10.1152/japplphysiol.91653.2008PubMed19336681History Published online 1 April 2009 Published in print 1 April 2009 Metrics

Local regulation of skin blood flow during cooling involving presynaptic P2 purinoceptors in rats

1. This study investigated a local effect of cooling on the plantar skin blood flow (PSBF) of tetrodotoxin-treated rats by laser-Doppler flowmetry. 2. When the air temperature around the left foot was locally cooled from 25 to 10 degrees C, the PSBF of the left foot decreased. 3. The response was inhibited by the alpha-adrenoceptor antagonist phentolamine, the alpha1-adrenoceptor antagonist bunazosin, the alpha2-adrenoceptor antagonist RS79948, and bretylium and guanethidine that inhibit noradrenaline release from sympathetic nerves. Adrenalectomy of the rats did not affect the cooling-induced response. 4. The P2 purinoceptor antagonists suramin and PPADS also significantly suppressed the cooling-induced reduction of PSBF. However, the inhibitory effect of PPADS on the cooling-induced response was abolished after the treatment with phentolamine. Intra-arterial injections of ATPgammaS, a stable P2 purinoceptor agonist, at 25 degrees C caused a transient decrease in PSBF in a dose-dependent manner, which was significantly inhibited by phentolamine and guanethidine. 5. These results suggest a novel mechanism for local cooling-induced reduction of skin blood flow in vivo; moderate cooling of the skin induces the release of ATP, which stimulates presynaptic P2 purinoceptors on sympathetic nerve terminals and facilitates the release of noradrenaline, thereby causing contractions of skin blood vessels via the activation of alpha1-and alpha2-adrenoceptors.

The Role of Non-Adrenergic Co-Transmitters in Regulation of Skin Blood Flow

The Role of Non-Adrenergic Co-Transmitters in Regulation of Skin Blood Flow

Influence of the Menstrual Cycle and Sex on the Skin Blood Flow Response to Tilting

0266 Women have decreased orthostatic tolerance compared with men, and anecdotal evidence suggests women are most susceptible to orthostatic intolerance in warm environments. Estrogen and progesterone are known to Influence the regulation of skin blood flow, and thus may impact the responses to an orthostatic challenge. PURPOSE: To examine sex differences and the Influence of the menstrual cycle on cutaneous vascular conductance (CVC) during orthostatic challenges in thermoneutral and heat stress conditions. METHODS: Three women not currently taking oral contraceptives (24±7 years) and 4 males (24±4 years) have been studied. Female subjects were studied during their early follicular, ovulatory, and midluteal menstrual cycle phases. Male subjects were studied twice within a 2–4 week period. Subjects underwent 2 head up tilt tests on an automatic tilt table. Tilts consisted of progressive 5 minute stages at 15°, 30°, 45° and 60° during thermoneutral conditions and again after a 0.5° C increase in core body temperature via whole body heating. An index of skin blood flow (RBC Flux) was measured by laser-Doppler flowmetery and (CVC) was calculated as RBC Flux/MAP. RESULTS: We observed similar decreases in CVC with increasing orthostatic stress in the thermoneutral condition between men and women in the early follicular and ovulatory phases. However, we observed a slight increase in CVC from baseline during the midluteal phase. During heat stress, CVC increased similarly in both sexes, but increased the most in the midluteal phase. When tilting was combined with heat stress the greatest decrease in CVC was observed during the midluteal phase. CONCLUSION: These preliminary data suggest the skin blood flow response to an orthostatic challenge differs in the midluteal verses other phases of the menstrual cycle. Supported by AHA grant 0265260Z

Influence of the Menstrual Cycle and Sex on the Skin Blood Flow Response to Tilting

0266 Women have decreased orthostatic tolerance compared with men, and anecdotal evidence suggests women are most susceptible to orthostatic intolerance in warm environments. Estrogen and progesterone are known to Influence the regulation of skin blood flow, and thus may impact the responses to an orthostatic challenge. PURPOSE: To examine sex differences and the Influence of the menstrual cycle on cutaneous vascular conductance (CVC) during orthostatic challenges in thermoneutral and heat stress conditions. METHODS: Three women not currently taking oral contraceptives (24±7 years) and 4 males (24±4 years) have been studied. Female subjects were studied during their early follicular, ovulatory, and midluteal menstrual cycle phases. Male subjects were studied twice within a 2–4 week period. Subjects underwent 2 head up tilt tests on an automatic tilt table. Tilts consisted of progressive 5 minute stages at 15°, 30°, 45° and 60° during thermoneutral conditions and again after a 0.5° C increase in core body temperature via whole body heating. An index of skin blood flow (RBC Flux) was measured by laser-Doppler flowmetery and (CVC) was calculated as RBC Flux/MAP. RESULTS: We observed similar decreases in CVC with increasing orthostatic stress in the thermoneutral condition between men and women in the early follicular and ovulatory phases. However, we observed a slight increase in CVC from baseline during the midluteal phase. During heat stress, CVC increased similarly in both sexes, but increased the most in the midluteal phase. When tilting was combined with heat stress the greatest decrease in CVC was observed during the midluteal phase. CONCLUSION: These preliminary data suggest the skin blood flow response to an orthostatic challenge differs in the midluteal verses other phases of the menstrual cycle. Supported by AHA grant 0265260Z

Der Kältereiz als therapeutisches Prinzip bei Neurodermitis

Atopic dermatitis (atopic eczema/dermatitis syndrome - AEDS, atopic or endogeneous dermatitis resp. eczema, neurodermitis) also is characterized by hyporegulation of small blood vessels with tendency to vasoconstriction in the skin. It is reported on own investigations confirming these findings in children, the influence of the North Sea climate on the regulation of skin blood flow and the therapeutical effect of the climatotherapy, also with regard to the normalization of further symptoms. In atopic dermatitis the physiological negative correlation between the humid cooling effect and the skin circulation is neutralized. In children two ways of reaction with an effect of normalization are typical. Cold stimuli are outstanding effective and result in an intensive reactive hyperaemia. The diminished humidity of the skin does not change under climatotherapy. Patients without skin symptoms should be treated as intensive as those with eczema of the joints or generalized eczema. Under treatment the dermatographism shows especially in patients with widespread atopic dermatitis a shift from white to red. Improvement of hyporegulation of small blood vessels, of their tendency towards constriction and thereby of skin symptoms can be achieved by intensive cold stimuli like air baths in gusty wind or baths in the sea.

Autonomic nervous function assessment using thermal reactivity of microcirculation

There are only a few reliable objective methods of diagnosing peripheral neuronal damage suitable for routine use; the most important is based on measurement of nerve conduction velocity, which only shows changes when severe disturbances are already present. However, it is precisely at this stage that the possibilities of therapy are no longer satisfactory. As small fibres are affected earlier in the course of most forms of PNP than the large ones, assessment of afferent as well as efferent C-fibre function gains importance in the management of this widespread disease. In assessment of autonomic dysfunction, variability of the heartbeat with deep breathing or the Valsalva manoeuvre is a good and generally accepted test, although not strongly associated with other PNP test abnormalities. However, axonal degeneration starts in the most distal parts of the axon due to impaired axonal transport. Therefore, the longest C-fibres, i.e. in the lower extremities, are affected first, and incipient changes are most prominent there. For this reason HLDF, a reflex response of the skin blood flow stimulated by heat, has advantages in assessment of early C-fibre dysfunction. Considering the fact that the afferent and efferent sympathetic C-fibres are involved in regulation of microcirculation, the skin blood flow regulation is investigated by means of laser Doppler flowmetry. The microcirculation is stimulated by heat and the reaction of microcirculation is assessed as a value for the function of afferent and efferent (sympathetic) C-fibres. The results of this method are in close correlation with electrophysiologic tests, which is not achieved with sudomotor function.