Lactate and Bicarbonate Uptake in the Sweat Duct of Cystic Fibrosis and Normal Subjects

Abstract

ABSTRACT. The sweat of single sweat glands of healthy MATERIALS AND METHODS individuals and cystic fibrosis patients was analyzed for differences in bicarbonate, lactate, and pH. These values were monitored as a function of sweat rate simultaneouslyThe method of sweat collection from single glands in viva has with 1) the electrical potential difference at the duct orifice been described in detail (I). In this study the sweat from a single (with respect to the interstitial fluid) and 2) the concentra-sweat gland on the volar surface of the forearm of nine CF tions of sodium, potassium, and chloride in surface sweat. patients and nine control subjects was collected in serial samples Sweat in both groups contained about equal concentrations over a period of 40 min. All CF patients had a confirmed of lactate and bicarbonate at similar sweat rates. Similarly, diagnosis from an established CF center. No two patients were the pH of sweat secreted at similar rates in the two on the same therapeutic regimen. All patients received various populations was not significantly different. Acidification of supplemental vitamins. All but one patient received pancreatic sweat increased with decreasing sweat rate. In both popu-enzyme supplements. All but one patient received various antilations, lactate and bicarbonate may be absorbed passively biotic therapy, but no two patients were treated with the same in the distal sweat duct in their nonionic form and, thus, regimen of antibiotics. Two patients did not use bronchodilator not influenced by the increased electrical potential differ-agents. All subjects were adolescents or older. The mean age of ence in the cystic fibrosis sweat duct. The uptake of these CF patients was 26.6 & 2.7 (SE) yr and of normal subjects was ions may involve active proton secretion by sweat duct 25.2 & 1.9 yr. Only one subject, a CF patient, was under 18 yr cells. (Pediatr Res 21: 79-82, 1987) of age. Because of the difficulty in performing a large number of HC03-and lactate microassays, only one sweat gland was seAbbreviations lected from a collection of about seven glands from each subject. The selected gland was chosen on the basis of its showing a wide CF, cystic fibrosis range in sweat rates. That is, since we were interested largely in PD, electrical potential difference the concentration change as a function of rate, we selected glands which gave the greatest difference in rates and which secreted throughout the collection period (30-40 min). The analysis of Na, K, and C1 in the sweat and the PD measurement were CF is a genetically inherited disorder predominantly affecting performed as described previously (I). Microvolumetric methods Caucasians. Pancreatic deficiency, pulmonary disease, and ele-were used measure (5) and lactate (6). vated sweat sodium and chloride levels are the foremost maniThe pH the sweat was measured by microfluorescence festations that characterize the disease. Present evidence suggest the ~H-sensitive fluorescent dye Dextran-FITC (Sigma; 10 mg/ that the elevated sodium...

Effect of age and gender on sweat lactate and ammonia concentrations during exercise in the heat

“…Our values are close to those already reported in men as "residual ions" (14), even though our calculations included ammonia. We did not find a strong inverse correlation between sweat H + and sweat SID (r = 0.1).…”

“…Although children's sweat Lac -after bout 1 was higher than that of adults, this cannot be accounted for by their lower SR. We found a negative but very weak association between SR and sweat Lac -(P > 0.05, r = -0.27, for all subjects). Such a relationship is not consistent since some investigators have reported an inverse correlation (7,8,24), while studies using single sweat glands have shown a significant positive correlation (14), or none at all (13).…”

“…Sweat Lacmay not be an accurate index of glycolytic rate of the sweat gland since some Lac -, in conjunction with other ions or in exchange with H + , is reabsorbed in the sweat duct (14,27).…”

“…One might predict that sweat pH would be lower in children than in adults for two reasons: the expected higher sweat Lac -in children and the increase of pH with SR (13,14). One possible way to prevent very low levels of sweat pH is to increase its NH 3 content.…”

V-type H+-ATPase in the human eccrine sweat duct: immunolocalization and functional demonstration

“…However, as it flows through the ductal portion of the gland, this fluid is modified by the reabsorption of solutes such as Na ϩ , Cl Ϫ , lactate, and HCO 3 Ϫ , leaving a hypotonic sweat (4, 32). Current models of ionic transport in the human eccrine sweat duct propose the presence of luminally located Na ϩ and Cl Ϫ channels and basolaterally located Na ϩ -K ϩ -ATPase, as well as K ϩ and Cl Ϫ channels (4,2,35,32,33,36). The pH of final sweat is a function of sweat rate, being as acidic as pH 5 when the sweat rate is low and increasing as sweat rate increases (22).…”