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1.
Effects of L-type voltage-gated Ca2+ channel blockade on cholinergic and thermal sweating in habitually trained and untrained men.
Amano, T, Fujii, N, Kenny, GP, Okamoto, Y, Inoue, Y, Kondo, N
American journal of physiology. Regulatory, integrative and comparative physiology. 2020;(5):R584-R591
Abstract
We evaluated the hypothesis that the activation of L-type voltage-gated Ca2+ channels contributes to exercise training-induced augmentation in cholinergic sweating. On separate days, 10 habitually trained and 10 untrained men participated in two experimental protocols. Prior to each protocol, we administered 1% verapamil (Verapamil, L-type voltage-gated Ca2+ channel blocker) and saline (Control) at forearm skin sites on both arms via transdermal iontophoresis. In protocol 1, we administered low (0.001%) and high (1%) doses of pilocarpine at both the verapamil-treated and verapamil-untreated forearm sites. In protocol 2, participants were passively heated by immersing their limbs in hot water (43°C) until rectal temperature increased by 1.0°C above baseline resting levels. Sweat rate at all forearm sites was continuously measured throughout both protocols. Pilocarpine-induced sweating in Control was higher in trained than in untrained men for both the concentrations of pilocarpine (both P ≤ 0.001). Pilocarpine-induced sweating at the low-dose site was attenuated at the Verapamil versus the Control site in both the groups (both P ≤ 0.004), albeit the reduction was greater in trained as compared with in untrained men (P = 0.005). The verapamil-mediated reduction in sweating remained intact at the high-dose pilocarpine site in the untrained men (P = 0.004) but not the trained men (P = 0.180). Sweating did not differ between Control and Verapamil sites with increases in rectal temperature in both groups (interaction, P = 0.571). We show that activation of L-type voltage-gated Ca2+ channels modulates sweat production in habitually trained men induced by a low dose of pilocarpine. However, no effect on sweating was observed during passive heating in either group.
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2.
Impact of 3-day high and low dietary sodium intake on sodium status in response to exertional-heat stress: a double-blind randomized control trial.
McCubbin, AJ, Lopez, MB, Cox, GR, Caldwell Odgers, JN, Costa, RJS
European journal of applied physiology. 2019;(9):2105-2118
Abstract
PURPOSE To determine the impact of altering dietary sodium intake for 3 days preceding exercise on sweat sodium concentration [Na+], and cardiovascular and thermoregulatory variables. METHODS Fifteen male endurance athletes (runners n = 8, cyclists n = 7) consumed a low (LNa, 15 mg kg-1 day-1) or high (HNa, 100 mg kg-1 day-1) sodium diet, or their usual free-living diet [UDiet, 46 (37-56) mg kg-1 day-1] for 3 days in a double-blind, randomized cross-over design, collecting excreted urine (UNa) and refraining from exercise. On day 4, they completed 2 h running at 55% [Formula: see text]O2max or cycling at 55% maximum aerobic power in Tamb 35 °C. Pre- and post-exercise blood samples were collected, and sweat from five sites using absorbent patches along the exercise protocol. RESULTS UNa on days 2-3 pre-exercise [mean (95% CI) LNa 16 (12-19) mg kg-1 day-1, UDiet 46 (37-56) mg kg-1 day-1, HNa 79 (72-85) mg kg-1 day-1; p < 0.001] and pre-exercise aldosterone [LNa 240 (193-286) mg kg-1 day-1, UDiet 170 (116-224) mg kg-1 day-1, HNa 141 (111-171) mg kg-1 day-1; p = 0.001] reflected sodium intake as expected. Pre-exercise total body water was greater following HNa compared to LNa (p < 0.05), but not UDiet. Estimated whole-body sweat [Na+] following UDiet was 10-11% higher than LNa and 10-12% lower than HNa (p < 0.001), and correlated with pre-exercise aldosterone (1st h r = - 0.568, 2nd h r = - 0.675; p < 0.01). Rectal temperature rose more quickly in LNa vs HNa (40-70 min; p < 0.05), but was similar at the conclusion of exercise, and no significant differences in heart rate or perceived exertion were observed. CONCLUSIONS Three day altered sodium intake influenced urinary sodium excretion and sweat [Na+], and the rise in rectal temperature, but had no effect on perceived exertion during moderate-intensity exercise in hot ambient conditions.
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3.
Sweat rate analysis of ivacaftor potentiation of CFTR in non-CF adults.
Kim, J, Farahmand, M, Dunn, C, Milla, CE, Horii, RI, Thomas, EAC, Moss, RB, Wine, JJ
Scientific reports. 2018;(1):16233
Abstract
To determine if ivacaftor (Kalydeco) influences non-CF human CFTR function in vivo, we measured CFTR-dependent (C-sweat) and CFTR-independent (M-sweat) rates from multiple identified sweat glands in 8 non-CF adults. The two types of sweating were stimulated sequentially with intradermal injections of appropriate reagents; each gland served as its own control via alternating off-on drug tests on both arms, given at weekly intervals with 3 off and 3 on tests per subject. We compared drug effects on C-sweating stimulated by either high or low concentrations of β-adrenergic cocktail, and on methacholine-stimulated M-sweating. For each subject we measured ~700 sweat volumes from ~75 glands per arm (maximum 12 readings per gland), and sweat volumes were log-transformed for statistical analysis. T-tests derived from linear mixed models (LMMs) were more conservative than the familiar paired sample t-tests, and show that ivacaftor significantly increased C-sweating stimulated by both levels of agonist, with a larger effect in the low cocktail condition; ivacaftor did not increase M-sweat. Concurrent sweat chloride tests detected no effect of ivacaftor. We conclude that ivacaftor in vivo increases the open channel probability (PO) of WT CFTR, provided it is not already maximally stimulated.
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4.
Sources of variance within and among young men in concentrations of 17β-estradiol and testosterone in axillary perspiration.
Elliott, B, Muir, C, deCatanzaro, D
Physiology & behavior. 2017;:23-29
Abstract
The most potent estrogen, 17β-estradiol (E2), and its precursor, testosterone (T), play critical roles in mammalian reproductive processes. Evidence indicates that these steroids are present in bioactive form in the excretions of many male mammals. It has been demonstrated that small lipophilic steroids such as E2 can be absorbed by proximate females from male excretions, arriving in the uterus, brain, and other organs where there are estrogen receptors. We took repeated samples of axillary perspiration from men aged 20-30years during vigorous exercise. Both steroids were consistently measurable, with concentrations that ranged from values comparable to those in facial perspiration and urine of both men and women to values that greatly exceeded concentrations observed in any other substrate of men and women. Inter-individual variance in axillary E2 was positively correlated with the extent of intimate experience with women, as assessed by a questionnaire, but unrelated to subjective measures of stress, exercise habits, or phytoestrogen content of diet. In addition, higher levels of axillary E2 were observed in participants when samples were collected by a female (as compared to a male) experimenter. These data are concordant with an hypothesis that male excretion of sex steroids could exert pro-reproductive influences on proximate females.
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5.
CORP: Improving the status quo for measuring whole body sweat losses.
Cheuvront, SN, Kenefick, RW
Journal of applied physiology (Bethesda, Md. : 1985). 2017;(3):632-636
Abstract
The measurement of whole body sweat losses (WBSL) is important to the study of body heat balance, body water balance, establishing guidelines for water and electrolyte consumption, and the study of metabolism and health. In principal, WBSL is measured by an acute change in body mass (ΔBM) in response to a thermoregulatory sweating stimulus. In this Cores of Reproducibility in Physiology (CORP) review, we revisit several basic, but rarely discussed, assumptions important to WBSL research, including the common equivalences: mass = weight = water = sweat. Sources of large potential measurement errors are also discussed, as are best practices for avoiding them. The goal of this CORP review is to ultimately improve the accuracy, reproducibility, and application of WBSL research.
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6.
Thermoregulation, Fluid Balance, and Sweat Losses in American Football Players.
Davis, JK, Baker, LB, Barnes, K, Ungaro, C, Stofan, J
Sports medicine (Auckland, N.Z.). 2016;(10):1391-405
Abstract
Numerous studies have reported on the thermoregulation and hydration challenges athletes face in team and individual sports during exercise in the heat. Comparatively less research, however, has been conducted on the American Football player. Therefore, the purpose of this article is to review data collected in laboratory and field studies and discuss the thermoregulation, fluid balance, and sweat losses of American Football players. American Football presents a unique challenge to thermoregulation compared with other sports because of the encapsulating nature of the required protective equipment, large body size of players, and preseason practice occurring during the hottest time of year. Epidemiological studies report disproportionately higher rates of exertional heat illness and heat stroke in American Football compared with other sports. Specifically, larger players (e.g., linemen) are at increased risk for heat ailments compared with smaller players (e.g., backs) because of greater body mass index, increased body fat, lower surface area to body mass ratio, lower aerobic capacity, and the stationary nature of the position, which can reduce heat dissipation. A consistent finding across studies is that larger players exhibit higher sweating rates than smaller players. Mean sweating rates from 1.0 to 2.9 L/h have been reported for college and professional American Football players, with several studies reporting 3.0 L/h or more in some larger players. Sweat sodium concentration of American Football players does not seem to differ from that of athletes in other sports; however, given the high volume of sweat loss, the potential for sodium loss is higher in American Football than in other sports. Despite high sweating rates with American Football players, the observed disturbances in fluid balance have generally been mild (mean body mass loss ≤2 %). The majority of field-based studies have been conducted in the northeastern part of the United States, with limited studies in different geographical regions (i.e., southeast) of the United States. Further, there have been a limited number of studies examining body core temperature of American Football players during preseason practice, especially at the high school level. Future field-based research in American Football with various levels of competition in hotter geographical regions of the United States is warranted.
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7.
Does Replacing Sodium Excreted in Sweat Attenuate the Health Benefits of Physical Activity?
Turner, MJ, Avolio, AP
International journal of sport nutrition and exercise metabolism. 2016;(4):377-89
Abstract
International guidelines suggest limiting sodium intake to 86-100 mmol/day, but average intake exceeds 150 mmol/day. Participants in physical activities are, however, advised to increase sodium intake before, during and after exercise to ensure euhydration, replace sodium lost in sweat, speed rehydration and maintain performance. A similar range of health benefits is attributable to exercise and to reduction in sodium intake, including reductions in blood pressure (BP) and the increase of BP with age, reduced risk of stroke and other cardiovascular diseases, and reduced risk of osteoporosis and dementia. Sweat typically contains 40-60 mmol/L of sodium, leading to approximately 20-90 mmol of sodium lost in one exercise session with sweat rates of 0.5-1.5 L/h. Reductions in sodium intake of 20-90 mmol/day have been associated with substantial health benefits. Homeostatic systems reduce sweat sodium as low as 3-10 mmol/L to prevent excessive sodium loss. "Salty sweaters" may be individuals with high sodium intake who perpetuate their "salty sweat" condition by continual replacement of sodium excreted in sweat. Studies of prolonged high intensity exercise in hot environments suggest that sodium supplementation is not necessary to prevent hyponatremia during exercise lasting up to 6 hr. We examine the novel hypothesis that sodium excreted in sweat during physical activity offsets a significant fraction of excess dietary sodium, and hence may contribute part of the health benefits of exercise. Replacing sodium lost in sweat during exercise may improve physical performance, but may attenuate the long-term health benefits of exercise.
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8.
Protocol for systematic review and meta-analysis: hop (Humulus lupulus L.) for menopausal vasomotor symptoms.
Abdi, F, Kazemi, F, Ramezani Tehrani, F, Roozbeh, N
BMJ open. 2016;(4):e010734
Abstract
INTRODUCTION Menopause is a critical stage in every woman's life. It can cause a distressing time for women by creating various vasomotor symptoms (VMS). Phytoestrogens can potentially exert various favourable effects and alleviate VMS in postmenopausal women. The hop (Humulus lupulus L.) contains 8-prenylnaringenin (8-PN), the most potent phytoestrogen known to date. The hop is eight times stronger than any other herbal oestrogens. This study aims to conduct a comprehensive systematic review and a meta-analysis survey of the effects of hop in the management of VMS in postmenopausal women. METHODS Only randomised controlled clinical trials, with cluster randomisation and crossover, blinded and non-blinded designs, conducted between 2000 and 2015, will be included in this review. Quasi-experimental and observational studies as well as case reports will be excluded. The studies will be selected if their participants were aged 40-60 years, had elevated follicle-stimulating hormone (FSH) levels and/or menstrual irregularities, and experienced discomforting VMS (at least hot flashes or night sweats). The primary outcome will be the rate of response to treatment, such as changes in frequency and intensity of symptoms in the intervention and placebo groups. 'Hop', 'Humulus', 'menopause', 'vasomotor', 'hot flashes', 'phytoestrogen' and 'night sweats' will be used as search key words. Prior to their inclusion in the review, the selected papers will be assessed by two independent reviewers for methodological validity. Any disagreements will be resolved through a third reviewer. The risk of bias will be independently determined using the Cochrane Risk of Bias Tool. The quality of the papers will be assessed based on the CONSORT checklist. ETHICS AND DISSEMINATION Results will be disseminated through traditional academic literature. Dissemination of results will occur by peer-reviewed publications. The results of our project can help reproductive health researchers when evaluating the discomforts of research procedures described in study protocols or when designing a study. Information on experiences of menopausal women involved in previous studies may also help in future research. The expected dissemination actions are effective treatment in designing strategies that aim to develop women's health and healthcare providers when offering treatment for women with vasomotor symptoms.
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9.
Oligonol supplementation modulates plasma volume and osmolality and sweating after heat load in humans.
Lee, J, Shin, Y, Murota, H
Journal of medicinal food. 2015;(5):578-83
Abstract
Oligonol is a low-molecular-weight polyphenol that possesses antioxidant and anti-inflammatory properties. This study investigated the effects of Oligonol supplementation on sweating response, plasma volume (PV), and osmolality (Osm) after heat load in human volunteers. We conducted a placebo-controlled crossover trial. Participants took a daily dose of 200 mg Oligonol or placebo for 1 week. After a 2-week washout period, the subjects were switched to the other study arm. As a heat load, half-body immersion into hot water (42°C±0.5°C for 30 min) was performed in an automated climate chamber. Tympanic and mean body temperature (Tty, mTb) and whole-body sweat loss volume (WBSLV) were measured. Changes in PV, Osm, and serum levels of aldosterone and sodium were analyzed. Oligonol intake attenuated increases in Tty, mTb, and WBSLV after heat load compared with the placebo (P<.01, P<.05, and P<.01, respectively). In addition, serum aldosterone was maintained at a relatively low degree and serum sodium was maintained at a relatively high degree with Oligonol compared to the placebo (P<.01 and P<.05, respectively). However, PV decreased and Osm increased significantly with Oligonol compared to the placebo (P<.05 and P<.05, respectively). This study demonstrates that Oligonol supplementation for 1 week can attenuate elevation of body temperature and excessive sweating under heat load in healthy humans, but interpretation of the results requires caution due to the potent diuretic effect of Oligonol.
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10.
Vasomotor symptoms in women and cardiovascular risk markers: Systematic review and meta-analysis.
Franco, OH, Muka, T, Colpani, V, Kunutsor, S, Chowdhury, S, Chowdhury, R, Kavousi, M
Maturitas. 2015;(3):353-61
Abstract
UNLABELLED We performed a systematic review and meta-analysis of the observational or interventional studies assessing the association of vasomotor symptoms (hot flushes and night sweats) with various cardiovascular risk markers (systolic (SBP) and diastolic blood pressure (DBP), hypertension, total cholesterol, body mass index (BMI), and measures of subclinical atherosclerosis), in peri-menopausal, menopausal, or postmenopausal women. Eleven unique studies were identified with data available on 19,667 non-overlapping participants. Pooled analysis showed that women with hot flushes, compared to those without, tended to have significant higher levels of SBP (mean difference (MD): 1.95 mmHg (95%CI, 0.27 to 33.63)), and DBP (MD 1.17 mmHg (95%CI, -0.21 to 2.54)) and higher odds of having hypertension (OR: 1.18, 95%CI: 0.93 to 1.51), albeit non-significant. Similarly, women who reported night sweats compared to those who did not, had significant higher levels of SBP, (MD: 1.33 mmHg (95%CI, 0.63 to 2.03)), DBP (MD: 0.55 mmHg (95%CI, 0.19 to 0.91)), total cholesterol (MD: 0.17 mmHg (95%CI, 0.03 to 0.31)) and BMI (MD: 0.64 mmHg (95%CI, 0.47 to 0.80)). Vasomotor symptoms in women were not associated with measures of subclinical atherosclerosis. Women with vasomotor symptoms may have an unfavorable cardiovascular risk profile compared to women without vasomotor complaints.