A modified,local sweat collector for warm and humid conditions

Summary The purpose of this study was to modify a previously described local sweat collector to facilitate the investigation of sweat rate and composition in a warm (30°C) and humid (relative humidity 80%) environment. The adherence of the collector to the skin was improved and a pouch was appended at the lower end of the collector. The limitations of the closed collector were examined by comparing the local sweat rate and the quantity of electrolyte excreted in sweat with those obtained using a second collector with a wide opening (to permit free evaporation) and by changes in the body mass. Eight subjects performed exercise on a cycle ergometer consisting of four equal periods of 15 min each, at 60% maximal oxygen consumption, with a rest of 5 min between each period. The sweat produced on a local skin area (85 cm², upper posterior thorax region) was collected at the end of each period, before measuring the body mass on a sensitive (±1 g) platform balance. The mean local sweat rate [2.61 (SEM 0.19) Mg-CM^–2. min^-1] was 2.4 times greater than the pro-rated whole body mass loss but the two were strongly correlated (r=0.82,P<0.01). Compared to the open collector, the greater quantity of electrolyte excreted into the closed collector would suggest that the conditions which prevailed in the closed collector, such as a higher local skin temperature, may have affected the function of the sweat gland. This method enabled the efficiency of local sweat evaporation to be assessed by measuring the difference between sweat volume collected in the open and in the closed collectors. Recovery of water volumes at rest indicated that no contamination and no apparent leakage occurred. This improved sweat collector is suitable for obtaining clean local sweat samples of up to 6 ml, and for measuring the sweat composition and also sweat rate during exercise in warm and humid conditions.     

Patch-clamp study of cultured human sweat duct cells: amiloride-blockable Na+ channel

The reabsorptive duct of the eccrine sweat gland has a large transepithelial conductance consisting mainly of a high conductance to Cl^– and a smaller, amiloride-blockable Na⁺ conductance (Bijman and Frömter 1986; Quinton 1985). Cells have been cultured from sweat ducts and their properties previously studied in Ussing chambers (Pedersen 1988) and with microelectrodes (Jones et al. 1988). We have now studied the ion channels present in excised, inside-out patches of human cultured sweat duct cells, and find a marked predominance of linear, 16 pS, amiloride-blockable, low selectivity, Na⁺ channels. Such channels were seen in 54/92 (59%) of the patches, with up to 7 channels recorded in a single patch.Other channel types were seen at much lower densities. The prevalence of an amiloride-blockable Na⁺ channel in cultured duct cells clearly distinguishes these cells from cultured sweat gland secretory cells, which lack such a channel.     

Intracellular potentials of toad urinary bladder

Short-circuited urinary bladders of Bufo marinus were impaled with microelectrodes. Intracellular potentials in the order of -80 mV were recorded. On inhibition of apical Na entry they hyperpolarized by about 15 mV and the fractional resistance of the apical membrane increased to near 1.0. These patterns are similar to those of other tight Na transporting amphibian epithelia. On two occasions, stable recordings from a single cell were obtained before and after oxytocin. Intracellular potential and fractional resistance of the apical membrane remained constant despite doubling of Na transport and cellular conductance. This finding suggests that oxytocin stimulates conductive pathways in both, apical and basolateral cell membranes of the toad urinary bladder.     

Renin-like (Angiotensinogenase) activity in human eccrine sweat

The presence of renin or renin-like activity (RLA) was demonstrated in human eccrine sweat incubated with purified sheep angiotensinogen, using rat bioassay and angiotensin I radioimmunoassay. Following cholinergic stimulation, sweat RLA was found to range between 0 (unmeasurable) and 266 ng/ml·h, i.e. RLA-values of sweat can be about 10 times higher than those of plasma. Therefore, renin synthesis in sweat glands could be assumed. RLA following activation of -adrenergic receptors by the administration of isoprenaline (Aludrin^®) did not exceed the mean values obtained by cholinergic activation. After \-adrenergic receptor blockade by propranolol (Dociton^®), RLA became unmeasurably low. Higher RLA-values were found after local injection of dibutyryl-c-AMP (90–210 ng/ml·h). The results indicate a \-adrenergic regulation of RLA-release in human sweat glands. Human sweat glands appear to be useful for studying extrarenal renin release.This work was supported by the Deutsche Forschungsgemeinschaft (Da 93/7)     

Recurrent endocrine mucin-producing sweat gland carcinoma

Endocrine mucin-producing sweat gland carcinoma is a rare skin tumor that most commonly involves the eyelid of elderly women. Morphologically and immunohistochemically, it is analogous to endocrine ductal carcinoma in situ of the breast and mammary solid papillary carcinoma; also, like the analogous breast lesion, there is an often associated invasive mucinous carcinoma with neuroendocrine differentiation. We describe the case of a 65-year-old woman with endocrine mucin-producing sweat gland carcinoma of the eyelid that recurred 3 years after an apparently complete excision.     

A simple and disposable sweat collector

Summary Apart from in cystic fibrosis, where sweat analysis provides valuable diagnostic information, sweat yields remain an overlooked biological fluid. Technical problems (dilution, condensation, contamination, evaporation, etc.) linked to currently available collection procedures are of concern and thwart their use. To overcome some of these technical difficulties, an original sweat-collection technique is described. A collection capsule is created inside a flexible, adhesive and disposable anchoring membrane pasted onto the skin. A fluid-tight window is positioned in the upper part of the pocket and gives access to its content. Through the collection window, complete emptying of the sweat collector can be achieved repeatedly by suction using a vacutainer tube inserted in a tube holder equipped with a long dull needle. With prior addition of a suitable marker, fractional samplings can also be performed using a precision micropipette. This collecting method allows for kinetic studies on sweat rate and sweat content. The limited bias-inducing manipulations linked to the described technique, coupled with the ease of performing kinetic studies on sweat volume and content, make this original tool a reliable and accurate sweat-collection technique.     

Vasoactive intestinal polypeptide receptor-like immunoreactivity in human sweat glands

Human sweat and sebaceous glands were studied immunohistochemically with a monoclonal antibody recognizing a vasoactive intestinal polypeptide (VIP) receptor. The staining pattern correlated well with the known distribution of sympathetic VIP-containing nerves in the human skin. The luminal cell layer of the sweat gland ducts and some acinar cells of the secretory coil of eccrine sweat glands were the major sites of VIP receptor-like immunoreactivity. From these findings and the known pharmacological actions of VIP it is concluded that a major role of VIP released from sympathetic nerves in the skin is to regulate chloride reabsorption from the primary sweat at the ductal segment.     

The relationship of sweat gland count to electrodermal activity

This study assessed whether greater skin conductance activity at the distal versus medial site (Scerbo, Freedman, Raine, Dawson, & Venables, 1992) is attributable to a greater number of active (open) sweat glands at the distal site. The number of sweat glands was measured using the Palmar Sweat Index (PSI). Twenty-four subjects were exposed to 10 auditory stimuli. Electrodes were placed on the fore and middle fingers of each hand, using distal sites on one hand and medial sites on the other. The PSI was measured at the medial and distal phalanges adjacent to the electrode placement sites. The distal site contained more open and total sweat glands. Open gland count had the strongest correlations with skin conductance. Multivariate analyses of covariance revealed that site effects for nonspecific and orienting response frequency and trials to habituation were associated with site differences in open glands. Skin conductance measures and the PSI reveal greater electrodermal activity at the distal site. In addition, the number of open glands may be a useful measure related to electrodermal response frequency when polygraph measurement is unavailable.     

Renin-like (angiotensinogenase) activity in sweat of patients with cystic fibrosis and controls

Summary Using bioassay method (rat blood pressure technique) as well as the radioimmunoassay, renin-like activity (RLA) was measured in eccrine sweat of patients with cystic fibrosis of the pancreas (CF) and of controls. Sweat-formation was induced by pilocarpine-iontophoresis or by local injection of carbamylcholine (Doryl®). RLA-values between 0 (not measurable) and 460 ng/ml·h were measured. With increasing sweat flow-rate a tendency to lower RLA-values was detected. No significant difference was observed between CF and controls. From the observation that RLA of sweat is up to 30 times higher than that of plasma, it is concluded that RLA is probably released not from plasma but from the sweat glands themselves, where it is stored or synthesized.This work was supported by the Deutsche Forschungsgemeinschaft     

Changes in the index of sweat ion concentration with increasing sweat during passive heat stress in humans

To investigate the pattern changes in the index of sweat ion concentration at skin surface with increasing sweat during passive heat stress in humans, we measured conductivity of the perfused water with sweat as the index of sweat ion concentration and sweat rate, continuously at the chest skin surface. Eight healthy subjects (22.4 ±1.0 years) were passively heated by lower-leg immersion in a hot water bath of 42°C for 50 min in an ambient temperature of 28°C and relative humidity of 50%. The internal temperature (Tor) thresholds of sweat rate and index of sweat ion concentration were almost similar. Concomitant onset for the index of sweat ion concentration and sweat rate occurred but two types of linear regression lines were identified in the relationship between the index of sweat ion concentration and sweat rate at a boundary sweat rate value of 0.30 ± 0.08 mg cm^–2 min^–1. The slope of the regression line at low levels of sweat (slope 0.02 ± 0.01 V mg^–1 cm^–2 min^–1) was significantly gradual compared with that at moderate levels of sweat (slope 0.30 ± 0.08 V mg^–1 cm^–2 min^–1) (P<0.05). These results suggest that at low levels of sweat the index of sweat ion concentration responds gradually with respect to sweat rate, which may be due to the ion reabsorption capacity of the sweat duct, and then the index of sweat ion concentration increased steeply with sweat rate.     

cAMP-induced chloride transport in NCL-SG3 sweat gland cells

cAMP-induced ion transport in a human sweat gland cell line, NCL-SG3, was investigated by X-ray microanalysis and patch-clamp technique. Stimulation with cAMP caused a decrease in the cellular Cl and K. cAMP had no significant effect on the intracellular Na and Ca. Chloride channel blockers (9-AC, DPC and NPPB) inhibited the cAMP-induced chloride efflux. In patch-clamp experiments the inward current increased over a period of 5–15 min on addition of membrane-permeable cAMP in 66% of the attempts when the cell was held at 0 mV and pulsed to negative membrane potentials. The inward current was completely blocked by chloride channel blockers. Washout reversed the effect of cAMP. The inward current was not diminished by substitution of impermeable cations for Na in the bath and was insensitive to TEA (tetraethylammoniumchloride). It is concluded that the inward current is mainly a chloride current. Cystic fibrosis transmembrane regulator (CFTR) could not be demonstrated in the NCL-SG3 cells. It is therefore possible that the chloride efflux is mediated by other types of chloride channels.     

Hydrogen ion and electrolyte excretion of the single human sweat gland

Summary pH, bicarbonate, sodium, potassium and lactate concentrations were measured in sweat from single human sweat glands.The interpretation of the results is that the gland duct reabsorbs bicarbonate from a bicarbonate-rich precursor fluid by means of proton excretion into the lumen. This process is carbonic anhydrase dependent and acetazolamide-sensitive. Moreover it is speculated, that intact hydrogen excretion may be essential for the reabsorption of sodium and the excretion of potassium by the gland duct.Lactate is excreted in human sweat in high concentrations (range 24 to 10 mMols/l). Within the pH range observed different grades of dissociation of lactate do not contribute significantly to the bicarbonate secretion.From the unaltered lactate concentrations after acetazolamide in final sweat it is concluded that the postulated H-Na-exchange mechanism consumes minimal amounts of energy which can not be detected with the applied method.Supported by Schweizerischer Nationalfonds and National Cystic Fibrosis Research Foundation of U.S.A. (NCFR).     

成年牦牛汗腺和皮脂腺的组织学特征

目的 探讨青海健康成年牦牛汗腺和皮脂腺的组织学特征。方法 从10头健康成年牦牛背部、肋部和腹部皮肤取样,运用HE、过碘酸-雪夫（PAS）和阿利新蓝-过碘酸-雪夫（AB-PAS）染色法,对汗腺和皮脂腺组织学结构进行观察与分析。结果 青海成年牦牛背部、肋部和腹部皮肤的汗腺为单管状腺,属于顶浆分泌型腺体,其分泌物为中性和酸性混合液,腺细胞胞质中含有糖原。皮脂腺呈葡萄状、多叶且分支的泡状腺,属于全浆分泌型腺体,其分泌物为中性黏液,腺细胞胞质中含有少量糖原。汗腺的密度、直径、长度和体积从背部到腹部呈递减趋势,但距离皮肤表面的深度呈递增趋势,且部位间差异显著(P<0.05)。皮脂腺的密度、导管部直径和长度、分泌部直径和长度及距离皮肤表面的深度从背部到腹部呈递减趋势,且部位间差异显著(P<0.05)。 结论 青海成年牦牛背部、肋部和腹部皮肤的汗腺和皮脂腺形态学结构相似,但其密度、大小和深度差异显著,且从背部到腹部存在渐变趋势。与其他牛类相比,牦牛汗腺和皮脂腺的密度高,但前者的分泌功能不发达而后者发达,这可能与其为了适应高原高寒环境有关。     

Cholinergic-induced oscillating transepithelial short-circuit current in cultured human sweat duct cells

Human sweat duct cells in primary culture were investigated by voltage-clamp technique. Stimulation with the muscarinic agonist, metacholine (MCh), produced an abrupt transient rise followed by sustained regular oscillations in the transepithelial short-circuit current (Iscc), which in these cells is carried by a mucosal amiloride-sensitive Na+ influx, secondary to a Ca2(+)-activated, voltage-dependent, large K+ shunt across the serosal membrane. The time of latency, the initial transient phase, and the sustained oscillating phase of the MCh-induced Iscc response were demonstrated to be differently affected by changes in temperature, agonist concentration and external Ca2+ supply. From these results a model is proposed for the MCh-induced signal transduction in cultured sweat duct cells, involving a primary intracellular oscillatory Ca2+ mobilization, activated by IPP, sustained by a temperature-regulated external Ca2+ supply, and counter-regulated by cytosolic Ca2+.     

Alterations during postnatal period in the secretory responsiveness of the sweat glands in rats to mecholyl

Summary A study was made to know the alterations in the secretory responsiveness of the plantar and palmar sweat glands to local administration of mecholyl in rats during postnatal period. Nonresponsiveness of the plantar and palmar sweat glands to mecholyl was observed in 0-to 16-day-old and 0-to 10-day-old rats, respectively. After the nonresponsive period, a gradual increase in the responsiveness to mecholyl was observed in the plantar sweat glands. In the palmar sweat glands, however, a rapid increase follwed by a temporary decrease and a subsequent gradual increase in the secretory responsiveness to mecholyl was found. This temporary decrease in the secretory responsiveness was observed on days soon after weaning.     

On the fine structure of horse sweat glands

Summary Sweat glands from different representative areas of the horse have been studied in 6 animals with light microscopy and the intermandibular and coccygeal regions from 2 animals with electron microscopy. The sweat glands were numerous and well developed in all areas examined. The columnar cells, dominated by secretory PAS-positive diastase resistant vesicles, were surrounded by myoepithelial cells resting on a well developed basal lamina. The cytoplasmic organelles characteristic for cells involved in secretion were present. The extensively folded basal plasma membrane, the numerous microvilli at the luminal border and the intraepithelial canaliculi lined with microvilli were morphological structures typical of cells involved in water and electrolyte transport. The observation of cytoplasmic protrusions were suggestive of apocrine secretion.On deputation from the Department of Anatomy, Bihar Veterinary College, Patna 14, Rajendra Agricultural University, Bihar, India. Supported by F.A.O. Veterinary Faculty for F.A.O.-Fellows and Scholars, Copenhagen, Denmark.     

Intracellular potentials in the isolated human cornea

Summary Intracellular potentials in the epithelium of the isolated human cornea were studied with 3 M KCl-filled microelectrodes. The average potential profile increased slightly and reached a maximal value in a depth of about 40 from the epithelial surface. The maximal potentials of 27.4±1.5 m V in a closed chamber of the Ussing-Zerahn type and 45.3±1.7 mV in an open chamber were constant up to 180 min after incubation. Using microelectrodes with high resistance the stromal potentials were close to 0 mV. Intracellular potentials were reduced by about 30% 2h after addition of 10^–3 M ouabain/l or 10^–3 M acetazolamide/l. A significant inhibition could be obtained 30 min after addition of the drugs. Ouabain in a dose of 10^–5 M/l showed no inhibitory effect. The data are consistent with the hypothesis of electrolyte transport systems (Na, Cl, HCO₃, H) located in the epithelium of the human cornea.Supported by Deutsche Forschungsgemeinschaft.     

Urea excretion in sweat during short-term efforts of high intensity

Summary The sweat urea excretion during different types of short-term efforts of high intensity was examined in well trained competitors. It has been found that considerable amounts of urea were excreted in the sweat during each exercise test investigated. It is concluded that the purine nucleotide cycle was the source of ammonia for the increased urea formation during the efforts.     

Detection of dermcidin-derived peptides in sweat by ProteinChip technology

Recently, a novel antimicrobial peptide DCD-1, derived from the Dermcidin (DCD) gene and secreted by sweat glands, has been described by Schittek et al. [Nat. Immunol. 2 (2001) 1133.]. Here we describe the application of the surface-enhanced laser desorption/ionisation (SELDI) technology for the detection of DCD-1 and other dermcidin-derived peptides directly from microlitre amounts of human sweat. The advantages of the technique are as follows: (a) it can be carried out with ease and rapidity; (b) multiple samples can be processed simultaneously; (c) prior purification is not required; and (d) only a limited sample volume is necessary for both protein profiling and semiquantitation. Profiling of human sweat from various donors revealed that in addition to DCD-1, other DCD-derived peptide species were also present in significant quantities. Four of five identified peptides were DCD-1 related, while the fifth corresponded to a portion of the DCD protein outside the DCD-1 core. This provides clues as to how the novel protein is processed to its active form, though further work remains to elucidate this fully. Thus, we have demonstrated the applicability of such technology to the detection of DCD-1 and for the protein profiling of sweat in general. Such studies could reveal valuable new biomarkers for diagnosis and treatment of skin and sweat gland disorders.     

Plasma ammonia is the principal source of ammonia in sweat

Summary Sweat contains ammonia. However, neither its source nor factors affecting its concentration in the sweat are known. The aim of this study was to examine the effect of plasma concentrations of ammonia and urea on the concentration of ammonia in the sweat. Four groups of male volunteers were examined: one control, two after ingestion of ammonium chloride, three cirrhotic, hyperammonaemic, four uraemic. Sweat was collected from each subject from the palmar side of the forearm using gauze pads, after previous iontophoresis of pilocarpine. Ammonia and urea concentrations were determined in the sweat and in the plasma. It was found that elevated plasma ammonia concentration in healthy subjects after ingestion of ammonium chloride as well in the cirrhotic patients resulted in an increase of ammonia concentration in the sweat. High plasma and sweat urea concentration in the uraemic subjects did not affect the concentration of ammonia in the sweat. It was concluded that plasma ammonia was the principal source of ammonia in the sweat.