Number Of Active Sweat Glands Research Articles

A 32-day long fieldwork in Antarctica improves heat tolerance during physical exercise.

We evaluated the influence of a 32-day camping in Antarctica on physical performance and exercise-induced thermoregulatory responses. In Brazil, before and after the Antarctic camping, the volunteers performed an incremental exercise at temperate conditions and, two days later, an exercise heat stress protocol (45-min running at 60% of maximum aerobic speed, at 31°C and 60% of relative humidity). In Antarctica, core temperature was assessed on a day of fieldwork, and average values higher than 38.5°C were reported. At pre- and post-Antarctica, physiological (whole-body and local sweat rate, number of active sweat glands, sweat gland output, core and skin temperatures) and perceptual (thermal comfort and sensation) variables were measured. The Antarctic camping improved the participants' performance and induced heat-related adaptations, as evidenced by sweat redistribution (lower in the chest but higher in grouped data from the forehead, forearm, and thigh) and reduced skin temperatures in the forehead and chest during the exercise heat stress protocol. Notwithstanding the acclimatization, the participants did not report differences of the thermal sensation and comfort. In conclusion, staying in an Antarctic camp for 32 days improved physical performance and elicited physiological adaptations to heat due to the physical exertion-induced hyperthermia in the field.

Nine-, but Not Four-Days Heat Acclimation Improves Self-Paced Endurance Performance in Females.

Although emerging as a cost and time efficient way to prepare for competition in the heat, recent evidence indicates that “short-term” heat acclimation (<7 days) may not be sufficient for females to adapt to repeated heat stress. Furthermore, self-paced performance following either short-term, or longer (>7 days) heat acclimation has not been examined in a female cohort. Therefore, the aim of this study was to investigate self-paced endurance performance in hot conditions following 4- and 9-days of a high-intensity isothermic heat acclimation protocol in a female cohort. Eight female endurance athletes (mean ± SD, age 27 ± 5 years, mass 61 ± 5 kg, VO2peak 47 ± 6 ml⋅kg⋅min−1) performed 15-min self-paced cycling time trials in hot conditions (35°C, 30%RH) before (HTT1), and after 4-days (HTT2), and 9-days (HTT3) isothermic heat acclimation (HA, with power output manipulated to increase and maintain rectal temperature (Trec) at ∼38.5°C for 90-min cycling in 40°C, 30%RH) with permissive dehydration. There were no significant changes in distance cycled (p = 0.47), mean power output (p = 0.55) or cycling speed (p = 0.44) following 4-days HA (i.e., from HTT1 to HTT2). Distance cycled (+3.2%, p = 0.01; +1.8%, p = 0.04), mean power output (+8.1%, p = 0.01; +4.8%, p = 0.05) and cycling speed (+3.0%, p = 0.01; +1.6%, p = 0.05) were significantly greater in HTT3 than in HTT1 and HTT2, respectively. There was an increase in the number of active sweat glands per cm2 in HTT3 as compared to HTT1 (+32%; p = 0.02) and HTT2 (+22%; p < 0.01), whereas thermal sensation immediately before HTT3 decreased (“Slightly Warm,” p = 0.03) compared to ratings taken before HTT1 (“Warm”) in 35°C, 30%RH. Four-days HA was insufficient to improve performance in the heat in females as observed following 9-days HA.

1345 Suppression of autophagy compromises sweat secretion in aged mice

Autophagy has been implicated in stress responses and cell differentiation in normal and diseased skin, however, the relative importance of autophagy in the various cell types of the skin is not fully understood. Here we investigated the role of autophagy in sweat glands of mouse models. The essential autophagy gene Atg7 was inactivated by Cre-lox recombination in keratin K14-positive precursor cells of epithelia and glands. The abundance of the autophagy substrate p62/sequestosome 1 was determined by immunofluorescence analysis. Sweat secretion was determined by the iodine-starch test on the soles of fully autophagy-competent control mice and mice carrying the epithelium-specific deletion of Atg7. The suppression of Atg7-dependent autophagy led to the accumulation of p62/sequestosome 1 (Sqstm1) in the secretory part of the sweat glands. Sweat secretion was normal in young Atg7f/f K14-Cre mice, but the number of active sweat glands was significantly reduced in Atg7f/f K14-Cre mice at an age of 10-14 months. These results suggest a previously unknown and possibly clinically relevant role of autophagy in the maintenance of sweat secretion during aging.

Number of Active Sweat Glands and its Reliability in Measurements Using Starch-Iodine Paper Method

The present study was aimed to assess the reliability of the Starch-Iodine method to count the number of active sweat glands (ASGs). A total of 192 samples was obtained from four body regions of eight subjects during 60-min leg immersion in 42oC water. Six raters participated in counting the number of ASGs using all the 192 samples (3 times (20, 40 and 60 min) * 4 sites (forehead, back, arm and hand) * 2 trials * 8 subjects). The results showed that 1) ASGs were the greatest on the forehead followed by the back, hand and forearm; 2) The number of ASGs from the six raters was on average 36±8 glands·cm−2 [min. 26 ~ max. 45]; 3) Correlation coefficients (r) between six raters were minimum .843 (p.001) and maximum .941 (p.001), which were both considered as being high enough; 4) Intra-class correlation coefficients (ICCs) in ASGs between six raters was .830 on average, which was classified as a good reliability between raters; and 5) ICCs was affected by the number of ASGs. A reliability was relatively low when the number of ASGs was a lower level (approximately below 10 glands·cmSUP-2/SUP) because several raters were confused at counting light, faint and fine spots, and a reliability between raters was relatively high when the number of ASGs was great enough (approximately 50~100 glands·cmSUP-2/SUP). For this reason, ASGs in the latter period than initial period of sweating, and on the head region than extremities might show greater reliabilities in the number of ASGs between raters.

Skin pretreatment with microneedles prior to pilocarpine iontophoresis increases sweat production

Collection of sweat via pilocarpine iontophoresis is commonly used to diagnose cystic fibrosis (CF), with thousands of tests performed each day. The main source of resistance to the passage of pilocarpine ions to the sweat glands is the electrical resistance of the stratum corneum. It was hypothesized that pretreating the skin with 0·5mm-long microneedles would significantly decrease this resistance, thus increasing pilocarpine's permeation into the skin. Improved permeation should result in significantly reduced time to sweat initiation, time to collection of a clinically meaningful amount of sweat, and increased total amount of sweat produced in 15min. Subjects (n=12) had two 5cm(2) areas on the forearm measured, marked and randomized to experimental (microneedles+iontophoresis) or control (iontophoresis alone). Microneedle pretreatment was conducted using a 35-needle microneedle stamp in a manner that 20 applications completely covered the 5cm(2) treatment area. This was repeated five times for a total of 100 applications. Both experimental and control sites were placed under iontophoresis (1·5mA) for 5min. Microneedle pretreatment significantly decreased mean skin resistance (260±27 kΩ versus 160±19 kΩ, P=0·006), while significantly increasing mean sweat rate (0·76±0·35 versus 0·54±0·19μl cm(2) min(-1) , P=0·007). No significant difference was found concerning pain (P=0·059), number of active sweat glands (P=0·627) or the osmolality of the collected sweat (P=0·636). The results of this study suggest that microneedle pretreatment prior to pilocarpine iontophoresis significantly increases sweat production. Such results have the potential to improve the methodology currently used to diagnose cystic fibrosis and, more broadly, to administer drugs via the skin.

Modified iodine-paper technique for the standardized determination of sweat gland activation

Quantifying sweat gland activation provides important information when explaining differences in sweat rate between populations and physiological conditions. However, no standard technique has been proposed to measure sweat gland activation, while the reliability of sweat gland activation measurements is unknown. We examined the interrater and internal reliability of the modified-iodine paper technique, as well as compared computer-aided analysis to manual counts of sweat gland activation. Iodine-impregnated paper was pressed against the skin of 35 participants in whom sweating was elicited by exercise in the heat or infusion of methylcholine. The number of active glands was subsequently determined by computer-aided analysis. In total, 382 measurements were used to evaluate: 1) agreement between computer analysis and manual counts; 2) the interrater reliability of computer analysis between independent investigators; and 3) the internal reliability of sweat gland activation measurements between duplicate samples. The number of glands identified with computer analysis did not differ from manual counts (68 ± 29 vs. 72 ± 24 glands/cm(2); P = 0.27). These measures were highly correlated (r = 0.77) with a mean bias ± limits of agreement of -4 ± 38 glands/cm(2). When comparing computer analysis measures between investigators, values were highly correlated (r = 0.95; P < 0.001) and the mean bias ± limits of agreement was 4 ± 18 glands/cm(2). Finally, duplicate measures of sweat gland activation were highly correlated (r = 0.88; P < 0.001) with a mean bias ± limits of agreement of 3 ± 29 glands/cm(2). These results favor the use of the modified-iodine paper technique with computer-aided analysis as a standard technique to reliably evaluate the number of active sweat glands.

Facing up to the imperceptible perspiration. Modulatory influences by diabetic neuropathy, physical exercise and antiperspirant

Sweating is variably altered by physical exercise, diabetic neuropathy and antiperspirants. Skin temperature, skin surface water loss (SSWL), the Corneometer(®) average capacitance (CMAC) and skin capacitance mapping (SCM) were measured before and after moderate physical exercise in 20 healthy subjects. The effect of 5% aluminium chloride hexahydrate (ACH) in a water solution was similarly tested. The same assessments were performed in 20 diabetic patients at rest. Diabetic neuropathy appeared at rest as an increased (compensatory) SCM on the forearms without obvious modification on the hypohidrotic legs. On ACH sites after exercise, SCM revealed both a lowered number of active sweat glands and a lighter stratum corneum (SC) (dryness). In addition, CMAC and SSWL were decreased on ACH sites at rest and at completion of exercise. In diabetic neuropathy, the compensatory hyperhidrosis is more easily disclosed than the hypohidrosis. ACH affects both sweat excretion and the SC hydration.

Localized β-adrenergic receptor blockade does not affect sweating during exercise

The purpose of the current study was to determine the effect of a locally administered nonselective β-adrenergic antagonist on sweat gland function during exercise. Systemically administered propranolol has been reported to increase, decrease, or not alter sweat production during exercise. To eliminate the confounding systemic effects associated with orally administered propranolol, we used iontophoresis to deliver it to the eccrine sweat glands within a localized area on one forearm prior to exercise. This allowed for determination of the direct effect of β-adrenergic receptor blockade on sweating during exercise. Subjects (n = 14) reported to the laboratory (23 ± 1°C, 35 ± 3% relative humidity) after having refrained from exercise for ≥12 h. Propranolol (1% solution) was administered to a 5-cm(2) area of the flexor surface of one forearm via iontophoresis (1.5 mA) for 5 min. A saline solution was administered to the opposing arm via iontophoresis. Each subject then exercised on a motor-driven treadmill at 75% of their age-predicted maximal heart rate for 20 min, while sweat rate was measured simultaneously in both forearms. Immediately after cessation of exercise, the number of active sweat glands was measured by application of iodine-impregnated paper to each forearm. The sweat rate for the control and propranolol-treated forearm was 0.62 ± 41 and 0.60 ± 0.44 (SD) mg·cm(-2)·min(-1), respectively (P = 0.86). The density of active sweat glands for the control and propranolol-treated forearm was 130 ± 6 and 134 ± 5 (SD) glands/cm(2), respectively, (P = 0.33). End-exercise skin temperature was 32.9 ± 0.2 and 33.1 ± 0.3°C for the control and propranolol-treated forearm, respectively (P = 0.51). Results of the current study show that when propranolol is administered locally, thus eliminating the potential confounding systemic effects of the drug, it does not directly affect sweating during the initial stages of high-intensity exercise in young, healthy subjects.

Distribuição regional do suor durante exercício progressivo até a fadiga

A partir da hipótese evolutiva de que a cabeça humana precisa ser resfriada de forma especial, o objetivo do presente estudo foi verificar se a sudorese seria maior na testa do que nas demais regiões do corpo durante o exercício progressivo até a fadiga (EPF). Em 17 voluntários (23 ± 2 anos, 76,93 ± 7,74 kg, 179 ± 7 cm e 1,9 ± 0,1 m²) foram medidos a taxa de sudorese local (TSlocal), o número de glândulas de suor ativas (GSA) e taxa de suor por GSA (TSlocal.GSA-1) em oito regiões do corpo (testa, costas, peito, braço, antebraço, mão, coxa e perna) durante o EPF em cicloergômetro. A TSlocal da testa foi maior que todas as outras regiões e a TSlocal do peito foi maior apenas que a da coxa. O número de GSA da testa foi maior do que em todas as outras regiões, e a GSA da mão foi maior que do peito, braço, coxa e perna. A TSlocal.GSA-1 da testa foi maior do que as do braço, antebraço, mão e coxa, e a TSlocal.GSA-1 das costas e do peito foram maiores que do antebraço e mão. A produção de suor da parte superior do corpo (testa, costas, peito, braço, antebraço, mão) foi maior que a inferior (coxa e perna). Concluiu-se que o EPF desencadeou um padrão de produção de suor maior na cabeça que pode estar relacionado à maior convecção nas regiões mais altas do corpo.

Relationship between sweat gland recruitment and esophageal temperature during exercise-induced hyperthermia

1. This study found four distinct phases of sweat gland recruitment could be identified during exercise-induced hyperthermia. 2. First, at rest there were no detectable active sweat glands. Second, as esophageal temperature increased consequent to the exercise bout, a threshold was reached and sweat gland recruitment was initiated. Next, sweat gland recruitment increased linearly with the increase in esophageal temperature ( r=0.78). Lastly, the number of active sweat glands reached a plateau at a maximum value. 3. These data support the hypothesis that sweat gland recruitment fits a proportional control model similar to other known thermoregulatory effectors. Furthermore, this is the first study to show that progressive sweat gland recruitment is a viable physiologic mechanism within localized skin sites.

Effect of tap-water iontophoresis on sweat gland recruitment, skin temperature and skin blood flow

Our interest was to quantify the role of sweat gland activation on the maintenance of skin temperature during mild exercise in the heat. Seven days of tap-water iontophoresis decreased the number of active sweat glands by 72% which significantly increased forearm skin temperature and blood flow during mild exercise (70 W) in the heat (32 °C). Skin temperature of the treated forearm was 0.5 °C warmer ( P=0.049); skin blood flow in the treated forearm was 13% higher than the control arm ( P=0.021). These results illustrate the importance of sweat evaporation on skin temperature and blood flow during exercise.

Functional requirement of aquaporin-5 in plasma membranes of sweat glands.

The distribution and function of aquaporins (AQPs) have not previously been defined in sweat glands. In this study, AQP1, AQP3, and AQP5 mRNA were demonstrated in rat paw by reverse transcription (RT)-PCR, but AQP2 and AQP4 were not. AQP1, AQP3, and AQP5 protein were confirmed in these tissues by immunoblotting. AQP1 was identified in capillary endothelial cells by immunohistochemical labeling, but not in sweat glands or epidermis. Abundant AQP3 expression was seen in basal levels of epidermis, but not in sweat glands. AQP2 and AQP4 were not observed in either skin or sweat glands. Immunohistochemical labeling revealed abundant AQP5 in secretory parts of rat and mouse sweat glands, where immunoelectron microscopy demonstrated abundant AQP5 labeling in the apical plasma membrane. AQP5 immunolabeling of human sweat glands yielded a similar pattern. To establish the role of AQP5 in sweat secretion, we tested the response of adult mice to s.c. injection of pilocarpine, as visualized by reaction of secreted amylase with iodine/starch. The number of active sweat glands was dramatically reduced in AQP5-null (-/-) mice compared with heterozygous (+/-) and wild-type (+/+) mice. We conclude that the presence of AQP5 in plasma membranes of sweat glands is essential for secretion, providing potential insight into mechanisms underlying mammalian thermoregulation, tactile sensitivity, and the pathophysiology of hyperhidrosis.

Effect of activated sweat glands on the intensity-dependent sweating response to sustained static exercise in mildly heated humans.

Changes in the number of activated sweat glands (ASGs) and sweat output per gland (SGO) with increased exercise intensity during sustained static exercise were investigated. Fourteen male subjects performed 20, 35, and 50% maximal voluntary contraction (MVC) for 60 s with the right hand (exercised arm) at an ambient temperature of 35 degrees C and 50% relative humidity. Although sublingual, local skin, and mean skin temperatures remained essentially constant throughout the exercise at each intensity, the sweating rate (SR) of nonglabrous skin on the nonexercised left forearm increased significantly with a rise in exercise intensity (p<0.05). Changes in the number of ASGs with rising exercise intensity paralleled changes in the SR, but the SGO did not change markedly with altered exercise intensity. These results suggest that in mildly heated humans, at less than 50% MVC, the increase in the SR from nonglabrous skin with rising exercise intensity during sustained static exercise is dependent on changes in the number of ASGs and not on SGO.

EFFECT OF SWEAT GLAND INACTIVATION ON SKIN TEMPERATURE AND SKIN BLOOD FLOW DURING EXERCISE IN THE HEAT

Sweat evaporation is the primary means for heat dissipation during exercise. The purpose of this study was to investigate the effect of sweat gland inactivation on sweat gland recruitment, skin temperature and skin blood flow during exercise in the heat. Nine subjects used tap-water iontophoresis with an electrical current of 7–20 mA on a 65 cm2 area of the anterior mid-forearm. Subjects were treated for 7 hr over seven consecutive days, and treatment to the non-dominant and dominant forearm was randomly assigned. After completing the treatment, subjects exercised at a light intensity (70 W) for 30 min in a warm environment (32°C, 50% RH) to promote sweating. Skin temperature and skin blood flow were measured during exercise at 0, 15, and 30 min with a YSI skin surface probe and a TSI laser Doppler, respectively. Immediately after exercise, sweat gland recruitment was measured with iodine-impregnated paper. The iontophoresis treatment decreased the number of active sweat glands by 75% which significantly increased skin temperature and skin blood flow. Post-hoc analysis indicated that the treated arm at 30 min was 0.6 °C warmer (P = 0.027) and had a 0.7 mol·100 ml−1 ·min−1 higher skin blood flow (P = 0.021). The data suggest that tap-water iontophoresis was an effective means of reducing sweat gland recruitment during exercise in the heat. These results illustrate the importance of sweat evaporation on skin temperature on skin temperature and skin blood flow for heat dissipation during exercise.

Limb vs trunk sweat gland recruitment patterns during exercise in humans

The purpose of this study was to examine the sweat gland recruitment pattern, on multiple trunk and limb sites, during exercise. Nineteen male volunteers performed 30 min of exercise on a cycle ergometer at approx. 25, 50 and 75% of their maximal oxygen uptake. The number of active sweat glands (per cm 2) was determined immediately following each exercise bout at the following six sites: left triceps, chest, back, forearm, thigh and calf. The data showed that increases in rectal temperature during exercise resulted in a linear increase in the absolute number of active sweat glands recruited at all six sites ( r=0.60–0.80). However, on a percentage basis, the limb sites increased proportionally more (300–600% increase) than the trunk sites (100–200% increase) with increases in rectal temperature. These data suggest that the absolute number of sweat glands recruited, on both the trunk and the limbs, increases in a linear manner with increases in rectal temperature during exercise. However, on a proportional basis, sweat gland recruitment on the limbs is greater than that found on the trunk during progressive exercise.

Instrumentation for Concurrent, Dynamic Monitoring of Active Sweat Glands and Perspiration Volume

A system for observing the active sweat glands on the thumb, and measuring of perspiration volume is proposed. The system is composed of a microscope with a CCD unit housed inside; stages for finding focused position; a VCR; a CRT; a sweat detecting probe; and a continuous local perspiration volume recorder. The areas covered by the focusing and by the detecting probe are 7 mm2 and 1 cm2, respectively. Maps of the sweat glands are prepared, and their activities are examined by monitoring and by using video tapes. The number of active sweat glands correlates with the amount of sweating; however the activity of sweat glands is found to be asynchronous. Individual glands' sweat secretion are graphed using timing charts. The sweat glands can be divided into three groups, namely, 1) very active, 2) only active under a strong impulse and 3) inactive. The present system may be useful for studying disorders and their therapies.

Changes in the number of active sweat glands (palmar sweat index, PSI) during a distressing film

Changes of the number of active palmar sweat glands (palmar sweat index, PSI) as assessed by the plastic finger-print method were studied in two groups of female students ( n = 21 each). In both samples experiments involved an initial adaptation period, several relaxation phases and an activation period (presentation of a movie). The film was shown 10 min earlier in Group 1, for which in turn follow-up was twice as long. Prints for determination of PSI were taken every 2.5 min from the forefinger and ring finger of the left hand, and recordings of SCL, SF (number of spontaneous fluctuations) and HR were made during the corresponding intervals. Both within-and between-groups comparisons showed an increase of PSI during the activation period and a decrease afterwards. Similar effects were observed for SCL, SF and affective and somatic arousal assessed by a state questionnaire. A decrease of PSI and parameters of electrodermal activity during the first measurements indicated an initial reaction to the assessment procedure itself. Both within-subject and between-subjects correlations between PSI from both fingers showed high parallel test reliabilities, while correlations with electrodermal variables indicated a common physiological basis.

The number of active palmar sweat glands (palmar sweat index, PSI) as an activation measure in field studies

The number of active sweat glands within a defined area of a fingertip, called the palmar sweat index (PSI), can be easily determined by means of the plastic fingerprint method. Two experiments were carried out to demonstrate the applicability of this technique in field research and to investigate the properties of the PSI as an activation parameter. In Experiment 1 (in a blood donors’ ward), PSI rose significantly during venous puncture and dropped after the cannula had been installed. In Experiment 2 (in a dental office), PSI values increased when patients were seated in the dental chair and rose to a higher level at the dentist’s entry. Values after treatment were significantly lower. In both experiments, it was observed that the initial assessments yielded higher PSI values. This is best explained as a reaction to the assessment procedure itself, and it is recommended that the first two prints not be used for the determination of baseline values.

Increases in sweat rate during exercise: Gland recruitment versus output per gland

1. 1.|Increase in exercise intensity result in linear ( r = 0.82) increases in whole-body sweat rate. 2. 2.|The total number of active sweat glands recruited increases significantly ( P < 0.05) with increases in exercise workload. 3. 3.|Mean sweat rate per gland is unchanged ( P > 0.05) with increases in exercise intensity. 4. 4.|Whole-body sweat rate is linearly ( r = 0.84) correlated to the number of active sweat glands recruited during exercise.

The determination of the antiperspirant activity of aluminium-chlorhydrate by digital image-analysis

Synopsis The method of Minor to visualize by iodine-starch-reaction the activity of sweat glands was used in combination with image-analysis to quantify sweat-secretion. Aqueous aluminium chlorohydrate solutions (ACH) (1, 2, 4, 8, 16%) were applied twice daily for 6 days to defined areas of the lower volar forearms. After 3 and 6 days of treatment perspiration was induced by thermal stress. The dark blue spots on top of active glands which are formed by iodine-starch-complexes were counted and their projection area was measured by an image analysing system. Increasing concentrations of ACH lower the number of active sweat glands, while the size of the dark spots is not dependent on the concentration of the active ingredient.