It is known that the concentrations of ammonia and lactate in blood increase during
incremental exercise. Sweat a Iso contains lactate and ammonia. The aim of the present
study was to investigate the physiological response of lactate and ammonia in plasma
and sweat during a stepwise incremental cycle ergometer exercise test in ten subjects.
During this test lactate and ammonia were measured in blood obtained from the earlobe
and in sweat collected in a bag attached to the back of the subject. At the end of
each interval this bag was emptied for measuring lactate and ammonia. A disproportional
increase in the concentration of lactate and ammonia in blood was found, in sweat
a disproportional decrease. The lactate concentrations in sweat were higher than those
in blood. We hypothesise that lactate in sweat is produced from glycogen granules
of the clear cell of the eccrine gland. This lactate production results in acidification
of sweat, which facilitates the diffusion of ammonia from eccrine duct cell to duct
lumen. It is uncertain how far duct cell ammonia originates from plasma, the duct
cell itself might produce ammonia. Part of the ammonia in sweat could come from the
breakdown of urea by skin bacteria.
Key words
Lactate - ammonia - sweat - blood - exercise - eccrine sweat gland
