Oscillatory processes in lymph microcirculation in the human skin

This study was the first to use laser Doppler flowmetry followed by wavelet analysis in order to estimate oscillations in lymph microcirculation in 30 subjects with (n = 13) or without (n = 17) edema of the distal part of the upper limb. Lymph flow in the human skin exhibited clear dominance of pacemaker phase oscillations in the frequency ranges of 0.021–0.042 and 0.016–0.035 Hz in the skin of the palm surface of the finger nail bone and in the skin of the forearm, respectively. Edema was associated with an increase in the peak frequencies and normalized maximum amplitudes (Al/Ml, where Al is the mean value of the maximum amplitude of phase oscillations, and Ml is the value of the averaged lymph flow expressed in perfusion units). Low-amplitude oscillations were recorded rarer in the myogenic, endothelial, and respiratory ranges. We did not find any cardiac pulse rhythm in the wavelet spectrum of the lymph flow. We did not find any interaction between the Al/Ml value and the skin temperature. In the group of subjects without edema, under physiological conditions only, we found a negative correlation between the Al/Ml value and the amplitudes of myogenous proper blood flow oscillations, which reflected the number of functional capillaries and activity of oxidative metabolism in the tissue. In the group with edema, we did not find any correlations between the indices of lymph flow and blood flow. The values of normalized amplitude and frequency of phase oscillations may be used as efficient diagnostic tools in the studies on lymph microcirculation.     

An Analysis of Phase Relationships between Oscillatory Processes in the Human Cardiovascular System

Biophysics - Abstract—The phase relationships between heart rate variability, respiration, forearm skin blood flow oscillations (according to laser Doppler flowmetry), and finger-pad tissue...     

Assessment of the changes in regulatory systems of human's skin blood flow during local heating

The mechanisms of thermal regulation of skin blood flow during local heating to 35, 40 and 45 'C have been studied by the method of laser Doppler flowmetry in healthy volunteers. To estimate the state of microvascular bed the continuous wavelet-transform spectral analysis has been used. The amplitudes of fluxmotions in the range of blood flow active modulation significantly increase during local heating to 35 degrees C. The amplitudes of blood flow oscillations in the ranges of cardiorhythm and respiratory rhythm increase during local heating to 40 degrees C. The high amplitude oscillations in the range of myogenic activity are maintained. The amplitude of oscillations in the range of endothelial activity distinctly decreases and the oscillations in the range of neurogenic activity are inhibited. Local heating to 45 degrees C results in a significant decreasing of the oscillation amplitudes in the range of myogenic activity, and the amplitudes of cardio- and respiratory spectral components amount to their peak values among the temperatures of local heating under study.     

Cross transfer effects of muscular training on blood flow in the ipsilateral and contralateral forearms

Blood flow in the right and left forearms was determined by venous occlusion plethysmography in ten healthy male subjects before and after training with a hand ergometer. The subjects in group A and B were trained using work loads of 1/3 and 1/2, respectively, of maximum grip strength 6 days/week for 6 weeks. It was found that the blood flow in the left (untrained or contralateral) forearm during exhaustive training of the right hand increased gradually with increasing training periods, and that after 6 weeks of training, grip strength, endurance and peak blood flow of the forearm increased significantly not only in the trained forearm, but also in the untrained forearm. From these results, it is suggested that the increase of blood flow in the contralateral limb after training may, at least in part, be related to the cross transfer effect of muscular endurance.     

Local heating of human skin by millimeter waves: effect of blood flow

We investigated the influence of blood perfusion on local heating of the forearm and middle finger skin following 42.25 GHz exposure with an open ended waveguide (WG) and with a YAV mm wave therapeutic device. Both sources had bell-shaped distributions of the incident power density (IPD) with peak intensities of 208 and 55 mW/cm(2), respectively. Blood perfusion was changed in two ways: by blood flow occlusion and by externally applied vasodilator (nonivamide/nicoboxil) cream to the skin. For thermal modeling, we used the bioheat transfer equation (BHTE) and the hybrid bioheat equation (HBHE) which combines the BHTE and the scalar effective thermal conductivity equation (ETCE). Under normal conditions with the 208 mW/cm(2) exposure, the cutaneous temperature elevation (DeltaT) in the finger (2.5 +/- 0.3 degrees C) having higher blood flow was notably smaller than the cutaneous DeltaT in the forearm (4.7 +/- 0.4 degrees C). However, heating of the forearm and finger skin with blood flow occluded was the same, indicating that the thermal conductivity of tissue in the absence of blood flow at both locations was also the same. The BHTE accurately predicted local hyperthermia in the forearm only at low blood flow. The HBHE made accurate predictions at both low and high perfusion rates. The relationship between blood flow and the effective thermal conductivity (k(eff)) was found to be linear. The heat dissipating effect of higher perfusion was mostly due to an apparent increase in k(eff). It was shown that mm wave exposure could result in steady state heating of tissue layers located much deeper than the penetration depth (0.56 mm). The surface DeltaT and heat penetration into tissue increased with enlarging the irradiating beam area and with increasing exposure duration. Thus, mm waves at sufficient intensities could thermally affect thermo-sensitive structures located in the skin and underlying tissue.     

The Impact of Stochastic Perturbations upon the Hydrodynamic Relationship between the Activity of Human Cardiac Ventricles and Low-Frequency Blood Flow Oscillations in the Microcirculatory Bed

Biophysics - Abstract—The experimentally revealed high phase coherence between low-frequency oscillations in the cutaneous blood perfusion signal at the contralateral skin sites indicates the...     

Dynamic autoregulation of cutaneous circulation: differential control in glabrous versus nonglabrous skin

The purpose of this project was to test the hypothesis that, independent of neural control, glabrous and nonglabrous cutaneous vasculature is capable of autoregulating blood flow. In 10 subjects, spectral and transfer function analyses of arterial pressure and skin blood flow (laser-Doppler flowmetry) from glabrous (palm) and nonglabrous (forearm) regions were performed under three conditions: baseline, ganglionic blockade via intravenous trimethaphan administration, and trimethaphan plus oscillatory lower body negative pressure (LBNP; -5 to -10 mmHg) from 0.05 to 0.07 Hz. Oscillatory LBNP was applied to regenerate mean arterial pressure variability that was abolished by ganglionic blockade. Ganglionic blockade was verified by an absence of a heart rate response to a Valsalva maneuver. Spectral power and transfer function gain between blood pressure and skin blood flow were calculated in this oscillatory frequency range (0.05-0.07 Hz). Within this frequency range, ganglionic blockade significantly decreased spectral power of blood flow in both the forearm and palm, whereas regeneration of arterial blood pressure oscillations significantly increased spectral power of forearm blood flow but not palm blood flow. During oscillatory LBNP, transfer function gain between blood pressure and skin blood flow was significantly elevated at the forearm (0.28 +/- 0.03 to 0.53 +/- 0.02 flux units/mmHg; P < 0.05) but was reduced at the palm (4.7 +/- 0.5 to 1.2 +/- 0.1 flux units/mmHg; P < 0.05). These data show that independent of neural control of blood flow, glabrous skin has the ability to buffer blood pressure oscillations and demonstrates a degree of dynamic autoregulation. Conversely, these data suggest that nonglabrous skin has diminished dynamic autoregulatory capabilities.     

Interactions between local and reflex influences on human forearm skin blood flow.

A three-part experiment was designed to examine interactions between local and reflex influences on forearm skin blood flow (SkBF). In part I locally increasing arm skin temperature (Tsk) to 42.5 degrees C was not associated with increases in underlying forearm muscle blood flow, esophageal temperature (Tes), or forearm blood flow in the contralateral cool arm. In part II whole-body Tsk was held at 38 or 40 degrees C and the surface temperature of one arm held at 38 or 42 degrees C for prolonged periods. SkBF in the heated arm rose rapidly with the elevation in body Tsk and arm Tsk continued to rise as Tes rose. SkBF in the arm kept at 32 degrees C paralleled rising Tes. In six studies, SkBF in the cool arm ultimately converged with SkBF in the heated arm. In eight other studies, heated arm SkBF maintained an offset above cool arm SkBF throughout the period of whole-body heating. In part III, local arm Tsk of 42.5 degrees C did not abolish skin vasoconstrictor response to lower body negative pressure. We conclude that local and reflex influences to skin interact so as to modify the degree but not the pattern of skin vasomotor response.     

Vasoconstriction during venous congestion: effects of venoarteriolar response, myogenic reflexes, and hemodynamics of changing perfusion pressure

We dissected the relative contribution of arteriovenous hemodynamics, the venoarteriolar response (VAR), and the myogenic reflex toward a decrease in local blood flow induced by venous congestion. Skin blood flow (SkBF) was measured in 12 supine subjects via laser-Doppler flowmetry 1) over areas of forearm and calf skin, in which the VAR was blocked by using eutectic mixture of local anesthetics (EMLA sites) and 2) over the contralateral forearm or calf skin (control sites), using two different techniques: limb dependency of 23-37 cm below the heart and cuff inflation to 40 mmHg. During limb dependency, SkBF decreased at the control sites, whereas it remained unchanged at the EMLA sites. In contrast, during cuff inflation, SkBF decreased at the control sites and also decreased at the EMLA sites. The percent change in SkBF from baseline was greater during cuff inflation than limb dependency at both the control sites and the EMLA sites. Estimated skin vascular resistance remained unchanged at the EMLA sites during cuff inflation, as well as limb dependency. Thus the decrease in SkBF during venous congestion with cuff inflation is not solely due to the cutaneous VAR but also to a reduction in local perfusion pressure. The VAR is therefore most specifically quantified by venous congestion induced by limb dependency, rather than cuff inflation. Finally, from both techniques, we calculated that during venous congestion induced by limb dependency (calf), approximately 45% of the nonbaroreflex vasoconstriction is induced by the VAR and approximately 55% by the myogenic reflex.     

Involvement of the sympatho-vagal balance in the formation of respiration-dependent oscillations in the human cardiovascular system

The effect of deep breathing controlled in both rate and amplitude on the heart rate variability (HRV) and respiration-dependent blood flow oscillations was studied in the forearm and finger-pad skin of healthy 18- to 25-year-old volunteers. In order to reveal the effects of the divisions of the autonomic nervous system on the amplitudes of respiratory sinus arrhythmia (RSA) and skin blood flow oscillations, we studied the indices of the cardiovascular system in two groups of subjects with respectively lower and higher values of the sympatho-vagal balance. This index was calculated as a ratio of low frequency and high frequency HRV spectral power (LF/HF) under the conditions of spontaneous breathing. It was found that, in subjects with a predominant parasympathetic tone, the amplitudes of RSA and the rate of blood flow in the finger-pad skin were higher compared to subjects with a predominant sympathetic tone during respiration with the frequency lower than 4 cycle/min. In the forearm skin, where sympathetic innervation is weaker compared to the finger-pad skin, there were no significant differences in respiration-dependent oscillations of the rate of blood flow in two groups of subjects.     

The influence of the sympathetic innervation on the skin microvascular tone and blood flow oscillations

The influence of the sympathetic innervation on the tone of resistive vessels and blood flow oscillations was studied using laser Doppler flowmetry and skin thermography in 18 healthy subjects (before and after reflex cold and heat tests and local thermal testing), 42 patients with denervation syndromes caused by median nerve damage, and 10 patients with an acute stage of aseptic inflammation after radius fracture. The blood flow oscillations in the range of neurogenic sympathetic influences (0.02–0.052 Hz) supported by low-frequency sympathetic rhythms are an essential component of neurovascular interrelations. The importance of these oscillations is determined by their contribution to an increase in tissue perfusion owing to a decrease in the peripheral resistance and also by the leveling of drastic changes in blood flow and stabilization of microhemodynamics upon pronounced changes in the stationary tone. The high-and low-frequency (tonic and oscillatory, respectively) sympathetic rhythmic activities are expressed in two ways: (1) a synchronous increase or decrease in their amplitudes and (2) frequency dominance. The reactivity of the vessel smooth muscles is an important factor in maintaining the blood flow oscillations. Denervation decreases the oscillation amplitude in the neurogenic range. Under the conditions of local “inflammatory sympatholysis,” reflex tonic effects, rather than oscillatory ones, of the sympathetic impulses are mainly suppressed. An isolated evaluation of the blood flow oscillations in the neurogenic sympathetic range cannot be a measure of sympathetic activity. In studies on its functional state and evaluation of the neurogenic tone (NT) of resistive vessels, it is necessary to take into account the parameters of both stationary and oscillatory components of the NT.     

Experimental studies on the effects of vibration and noise on sympathetic nerve activity in skin

Multi-unit sympathetic activity was recorded at elbow level from median nerve fascicles supplying glabrous skin of the left hand in five healthy subjects. The resultant vasomotor responses accompanying the neural activity were monitored by simultaneous recordings of skin blood flow using the laser doppler method and skin temperature in the innervation zones. No significant change in sympathetic activity was observed during handgrip exercise of the right hand under a constant gripping force of 2 kg. Subjects maintained the same gripping force of the right hand during exposure in random order to local vibration and/or noise, each type of exposure lasting 5 min with intervals of 20 min. A two-peaked significant increase in outflow from sympathetic nerves was observed during local exposure of the right hand to vibration with a frequency of 60 Hz and an acceleration of 50 m.s-2, followed by a postexposure period which revealed a relative suppression of sympathetic nerve activity and a significant increase in blood flow. Noise at 100 dB(A) showed only an initial effect on skin sympathetic nerve activity (SSA), whereas when combined with local vibration at 60 Hz, a pronounced increase in neural activity was noticed, indicating a combined effect of vibration and noise. These results from direct recordings of SSA suggest a sympathetic vasomotor reflex mechanism triggered by local vibration stimuli to the hand.     

Influence of sensory peptidergic innervation on human skin blood flow oscillations in the range 0.047–0.069 Hz

Thirty-six healthy subjects and 65 patients with neurogenic inflammation (complex regional pain syndrome of the hand) or denervation syndromes (after median and ulnar nerve injuries or transplantation of denervated vascularized musculocutaneous autografts), as well as after thoracoscopic sympathectomy, underwent laser Doppler flowmetry with spectral wavelet analysis of the blood flow oscillations in cutaneous microvessels and thermography. It was shown that, along with maintenance of the blood flow oscillations of endothelial genesis, peptidergic sensory nerve fibers (SPFs) are involved in activating independent, including high-amplitude, oscillations in the myogenic range 0.047–0.069 Hz (an average of three to four oscillations per minute). The above-mentioned oscillations were recorded against the background of neurogenic inflammation and nociceptive activation of C afferents after nerve injuries, as well as in the course of functional tests in healthy subjects (the forearm skin electrostimulation test, capsaicin application). Sympathectomy and hyposympathicotonia contributed to their manifestation; they were not detected under the conditions of severe sensory-trophic skin denervation. The appearance of high-amplitude blood flow oscillations in human skin microvessels at a frequency of 0.047–0.069 Hz may serve as an objective criterion of SPF activation.     

Effect of high local temperature on reflex cutaneous vasodilation

We examined the effect of high local forearm skin temperature (Tloc) on reflex cutaneous vasodilator responses to elevated whole-body skin (Tsk) and internal temperatures. One forearm was locally warmed to 42 degrees C while the other was left at ambient conditions to determine if a high Tloc could attenuate or abolish reflex vasodilation. Forearm blood flow (FBF) was monitored in both arms, increases being indicative of increases in skin blood flow (SkBF). In one protocol, Tsk was raised to 39-40 degrees C 30 min after Tloc in one arm had been raised to 42 degrees C. In a second protocol, Tsk and Tloc were elevated simultaneously. In protocol 1, the locally warmed arm showed little or no change in blood flow in response to increasing Tsk and esophageal temperature (average rise = 0.76 +/- 1.18 ml X 100 ml-1 X min-1), whereas FBF in the normothermic arm rose by an average of 8.84 +/- 3.85 ml X 100 ml-1 X min-1. In protocol 2, FBF in the normothermic arm converged with that in the warmed arm in three of four cases but did not surpass it. We conclude that local warming to 42 degrees C for 35-55 min prevents reflex forearm cutaneous vasodilator responses to whole-body heat stress. The data strongly suggest that this attenuation is via reduction or abolition of basal tone in the cutaneous arteriolar smooth muscle and that at a Tloc of 42 degrees C a maximum forearm SkBF has been achieved. Implicit in this conclusion is that local warming has been applied for a duration sufficient to achieve a plateau in FBF.     

Blood flow oscillations at a frequency of about 0.1 Hz in skin microvessels do not reflect the sympathetic regulation of their tone

Wavelet analysis of blood flow oscillations recorded with laser Doppler flowmetry in finger glabrous skin microvessels was carried out in 82 subjects with different variations in the syndromes of hand and foot sympathectomy and denervation. As distinct from the 0.02–0.046-Hz (about 0.03–0.04 Hz) blood flow oscillations in skin microvessels of sympathetic thermoregulatory origin, no relationship was found between the presence of 0.07–0.015 Hz (about 0.1 Hz) vasomotions in the wavelet spectrum and intactness of sympathetic innervation in the tissue region. The use of the myogenic band oscillation parameters, in particular, the amplitudes of vasomotions, for assessing the state of sympathetic thermoregulatory innervation determining the neurogenic tone of skin microvessels is not physiologically correct. The influence of local environmental factors on the vasomotion parameters confirms their local origin. The local perfusion pressure value significantly influenced the amplitude but not the frequency of vasomotions. The amplitude dominance of vasomotions was observed upon a decrease in perfusion pressure, whereas a marked increase in perfusion pressure or venous congestion resulted in a sharp depression of their amplitudes. Under the sympathectomy conditions, the oscillatory dynamic component of the arteriolar myogenic tone in the glabrous skin of the extremity acral zones is involved in the blood flow’s autoregulation. The presence of fine sensory fibers is necessary to carry out the dynamic autoregulation of the blood flow. Sensory nonmyelinated fibers and the trophic neuropeptides secreted by them not only initiate independent oscillations in the low-frequency (0.047–0.069 Hz) myogenic band, but also contribute to the normalized amplitudes of vasomotions being increased. At the same time, no appreciable influence of the sympathetic vasomotor activity and the corresponding influence of catecholamines on the amplitude and frequency of vasomotions was observed.     

6-OHDA帕金森病大鼠快动眼睡眠状态下皮层脑电及基底节场电位的异常变化

目的：了解帕金森病（PD）模型大鼠在快动眼睡眠状态下皮层脑电和基底节场电位的异常变化。方法：用6-羟基多巴胺（6-OHDA）脑内两点注射法建立PD大鼠模型,并经阿扑吗啡注射诱发旋转对模型进行评价。通过多导宏电极在体电生理记录技术结合视频录像,对正常大鼠和6-OHDA大鼠PD模型进行苍白球场电位和皮层M1、M2区脑电的多部位24小时同时记录。功率谱分析和相干分析用于揭示快动眼睡眠状态下各记录位点信号的频率成分以及不N记录位点神经元集群之间的变化。结果：与正常大鼠相比,6-OHDA帕金森病模型大鼠在REM期间的皮层脑电在臼和y频段上都有变化：初级运动皮质M1区的θ频段成分消失,辅助运动区M2的θ频段成分略有增加,患侧苍白球的θ频段成分增大显著;M1区的γ频段成分增大,而γ频段成分在苍白球基本没有变化。结论：6-OHDA对中脑多巴胺能神经元的损害可造成大鼠双侧皮层M1区θ节律的消失和γ节律的增强,以及对侧M1-M2区之间在γ节律上的同步被显著增强,而γ节律在苍白球没有变化。这些异常电活动可能是由于VTA受损引起从而与帕金森病的快动眼睡眠行为障碍有关。     

Differential control of forearm and calf vascular resistance during one-leg exercise

The purpose of this study was to determine whether blood flow (BF) and vascular resistance (VR) are controlled differently in the nonactive arm and leg during submaximal rhythmic exercise. In eight healthy men we simultaneously measured BF to the forearm and calf (venous occlusion plethysmography) and arterial blood pressure (sphygmomanometry) and calculated whole limb VR before (control) and during 3 min of cycling with the contralateral leg at 38, 56, and 75% of peak one-leg O2 uptake (VO2). During the initial phase of exercise (0-1.5 min) at all work loads, BF increased and VR decreased in the forearm (P less than 0.05), whereas calf BF and VR remained at control levels. Thereafter, BF decreased and VR increased in parallel and progressive fashion in both limbs. At end exercise, forearm BF and VR were not different from control values (P greater than 0.05); however, in the calf, BF tended to be lower (P less than 0.05 at 75% peak VO2 only) and VR was higher (23 +/- 9, 44 +/- 14, and 88 +/- 23% above control at 38, 56, and 75% of peak VO2, respectively, all P less than 0.05). In a second series of studies, forearm and calf skin blood flow (laser-Doppler velocimetry) and arterial pressure were measured during the same levels of exercise in six of the subjects. Compared with control, skin BF was unchanged and VR was increased (P less than 0.05) in the forearm by end exercise at all work loads, whereas calf skin BF increased (P less than 0.05) and VR decreased (P less than 0.05). The present findings indicate that skeletal muscle and skin VR are controlled differently in the nonactive forearm and calf during the initial phase of rhythmic exercise with the contralateral leg. Skeletal muscle vasodilation occurs in the forearm but not in the calf; forearm skin vasoconstricts, whereas calf skin vasodilates. Finally, during exercise a time-dependent vasoconstriction occurs in the skeletal muscle of both limbs.     

Oscillation of the electric potential of frog skin under the effect of Li+: Experimental approach

Summary When a frog skin is used to separate two compartments, and lithium is added to the external medium, transmembrane electric potential oscillations frequently occur. When no external current is imposed, sustained oscillations, with a period of about 10 min, are maintained for several hours. An oscillation of the Na⁺ influx accompanies the electric oscillation, though the two oscillations are out of phase to a greater or less extent.Theophyllin promotes a significant decrease in the mean electric potential of the skin, but it does not affect very much the characteristics of the oscillation. Important factors influencing the oscillation are temperature, permeability of the external membrane to lithium, and potassium concentration in the internal medium. No correlation can be detected between oscilation characteristics and skin area. This suggests that the oscillation is of a local nature, possibly originating at the cellular level. Occurrence of macroscopic oscillations implies coupling between local oscillators. Coupling between two epithelia has been studied under diverse conditions. The coupling is of an electrical nature: by varying the value of the coupling resistance, it is possible to control synchronization of the oscillations.     

Synaptic patterning of left-right alternation in a computational model of the rodent hindlimb central pattern generator

Establishing, maintaining, and modifying the phase relationships between extensor and flexor muscle groups is essential for central pattern generators in the spinal cord to coordinate the hindlimbs well enough to produce the basic walking rhythm. This paper investigates a simplified computational model for the spinal hindlimb central pattern generator (CPG) that is abstracted from experimental data from the rodent spinal cord. This model produces locomotor-like activity with appropriate phase relationships in which right and left muscle groups alternate while extensor and flexor muscle groups alternate. Convergence to this locomotor pattern is slow, however, and the range of parameter values for which the model produces appropriate output is relatively narrow. We examine these aspects of the model’s coordination of left-right activity through investigation of successively more complicated subnetworks, focusing on the role of the synaptic architecture in shaping motoneuron phasing. We find unexpected sensitivity in the phase response properties of individual neurons in response to stimulation and a need for high levels of both inhibition and excitation to achieve the walking rhythm. In the absence of cross-cord excitation, equal levels of ipsilateral and contralateral inhibition result in a strong preference for hopping over walking. Inhibition alone can produce the walking rhythm, but contralateral inhibition must be much stronger than ipsilateral inhibition. Cross-cord excitatory connections significantly enhance convergence to the walking rhythm, which is achieved most rapidly with strong crossed excitation and greater contralateral than ipsilateral inhibition. We discuss the implications of these results for CPG architectures based on unit burst generators.     

Effect of hand heating by a warm air box on O2 consumption of the contralateral arm.

Arterialization of venous blood is often used in studying forearm metabolism. Astrup et al. [Am. J. Physiol. 255 (Endocrinol. Metab. 18): E572-E578, 1988] showed that heating of the hand by a warming blanket caused a redistribution of blood flow in the contralateral arm and thus introduced errors in forearm skeletal muscle flux calculations. The present study was undertaken to investigate how hand heating by a warm air box (60 degrees C) would affect metabolism and blood flow in the contralateral arm before and during 3 h after a glucose load. Eleven healthy volunteers (5 males, 6 females) underwent an oral glucose tolerance test (70 g) on two different occasions, one test with and one without heating of the contralateral hand, in random order. Heating the hand for 30 min before glucose intake did not affect skin temperature, rectal temperature, deep venous oxygen saturation, forearm blood flow, or oxygen consumption of forearm skeletal muscle. Although, after the glucose load, heating significantly increased forearm blood flow (P less than 0.05), the integrated response after glucose was not significantly different between control and heating experiments [67 +/- 43 and 117 +/- 41 (SE) ml/100 ml tissue]. With both conditions, there was an increase in skin temperature (P less than 0.001, integrated response control: 369 +/- 79 and heating: 416 +/- 203 degrees C) and oxygen consumption of forearm muscle (control: 290 +/- 73, P less than 0.05 and heating: 390 +/- 130 mumol/100 ml, P less than 0.05) after glucose intake. These responses did not significantly differ between the conditions.(ABSTRACT TRUNCATED AT 250 WORDS)