title: Sweat constitutes several natural moisturizing factors, lactate, urea, sodium, and potassium.
abstract: BACKGROUND
  Amino acids (AAs) play important roles in maintaining an optimal hydration state of stratum corneum (SC) as a natural moisturizing factor (NMF). Recently, however, we have reported that lactate and potassium significantly affect the hydration state of SC.
  
  
  OBJECTIVE
  To explore the source of lactate and potassium in SC, we compared the concentration of various NMFs such as AAs, pyrrolidone carbonic acid (PCA), lactate, sodium, and potassium in SC between anhidrotic and adjacent hidrotic areas of patients with acquired idiopathic generalized anhidrosis or segmental anhidrosis.
  
  
  METHODS
  We examined 13 anhidrotic areas and the adjacent hidrotic skin of 10 different patients. We first determined anhidrotic and hidrotic areas of each patient by the iodine starch method and examined the hydration state of SC by measuring the high-frequency conductance. Then we obtained SC by tape stripping and measured the content of AAs, PCA, lactate, urea, sodium, and potassium in SC obtained from the anhidrotic and hidrotic areas. We examined the effect of increased insensible perspiration on the SC hydration and the concentrations of NMFs.
  
  
  RESULTS
  The SC of anhidrotic areas showed significantly low hydration. Among NMFs, lactate, urea, sodium, and potassium were significantly decreased in the SC of anhidrotic areas, while AAs and PCA were not significantly different between hidrotic and anhidrotic areas. Increased insensible perspiration increased SC hydration as well as NMFs other than AAs and PCA.
  
  
  CONCLUSIONS
  Sweat constitutes lactate, urea, sodium, and potassium in NMFs and plays a crucial role in maintaining the physiological hydration state of SC.
authors.affiliation: Department of Dermatology, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Watabe
authors.forename: Tomoko
authors.initials: T
authors.lastname: Sugawara
authors.forename: Katsuko
authors.initials: K
authors.lastname: Kikuchi
authors.forename: Kenshi
authors.initials: K
authors.lastname: Yamasaki
authors.forename: Shingo
authors.initials: S
authors.lastname: Sakai
authors.forename: Setsuya
authors.initials: S
authors.lastname: Aiba
mesh_terms: D000293:Adolescent; D000328:Adult; D000596:Amino Acids / Q000737:chemistry; D002255:Carbonic Acid / Q000737:chemistry; D004817:Epidermis / Q000378:metabolism; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007007:Hypohidrosis; D007223:Infant; D007773:Lactates / Q000737:chemistry*; D008297:Male; D008875:Middle Aged; D011188:Potassium / Q000737:chemistry*; D011760:Pyrrolidinones / Q000737:chemistry; D012867:Skin / Q000378:metabolism / Q000473:pathology; D012964:Sodium / Q000737:chemistry*; D013542:Sweat; D014508:Urea / Q000737:chemistry*
chemical_list: D000596:Amino Acids; D007773:Lactates; D011760:Pyrrolidinones; D002255:Carbonic Acid; D014508:Urea; D012964:Sodium; D011188:Potassium
keywords: Amino acid; Anhidrosis; Lactate; Natural moisturizing factor; Pyrrolidone carbonic acid; Urea