Effect of induced metabolic alkalosis on sweat composition in men.
To determine whether induced metabolic alkalosis affects sweat composition, 10 males cycled for 90 min at 62.5 +/- 1.3% peak oxygen uptake, on two separate occasions. Subjects ingested either empty capsules (placebo) or capsules containing NaHCO3- (0.3 g kg-1 body mass; six equal doses) over a 2-h period, which commenced 3 h prior to exercise. Arterialized-venous blood samples were drawn prior to and after 15, 30, 60 and 90 min of exercise. Sweat was aspirated at the end of exercise from a patch located on the right scapula region. NaHCO3- ingestion elevated blood pH, [HCO3-] and serum [Na+], whereas serum [Cl-] and [K+] were reduced, both at rest and during exercise (P < 0.05). Sweat pH was greater in the NaHCO3- trial (6.24 +/- 0.18 vs. 6.38 +/- 0.18; P < 0.05), whereas sweat [Na+] (49.5 +/- 4.8 vs. 50.2 +/- 4.3 mEq L-1), [Cl-] (37.5 +/- 5.1 vs. 39.3 +/- 4.2 mEq L-1) and [K+] (4.66 +/- 0.19 vs. 4.64 +/- 0.34 mEq L-1) did not differ between trials (P > 0.05). Sweat [HCO3-] (2.49 +/- 0.58 vs. 3.73 +/- 1.10 mEq L-1) and [lactate] (8.92 +/- 0.79 vs. 10.51 +/- 0.32 mmol L-1) tended to be greater after NaHCO3- ingestion, although significance was not reached (P=0.07 and P=0.08, respectively). These data indicate that induced metabolic alkalosis can modify sweat composition, although it is unclear whether the secretory coil, reabsorptive duct, or both are responsible for this alteration.
Patterson
M J
MJ
Strathclyde Institute for Biomedical Sciences, University of Strathclyde, Glasgow, Scotland, UK.
Galloway
Stuart D R
SD
Nimmo
M A
MA
D000328:Adult; D000471:Alkalosis / Q000139:chemically induced / Q000378:metabolism*; D001639:Bicarbonates / Q000032:analysis / Q000378:metabolism; D002712:Chlorides / Q000032:analysis / Q000378:metabolism; D005080:Exercise Test; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007773:Lactates / Q000032:analysis / Q000378:metabolism; D008297:Male; D011188:Potassium / Q000032:analysis / Q000378:metabolism; D012964:Sodium / Q000032:analysis / Q000378:metabolism; D017693:Sodium Bicarbonate / Q000494:pharmacology*; D013542:Sweat / Q000737:chemistry / Q000378:metabolism*
D001639:Bicarbonates; D002712:Chlorides; D007773:Lactates; D017693:Sodium Bicarbonate; D012964:Sodium; D011188:Potassium