Do the eccrine glands of the skin function in absorbing oxygen during the salt
recycling process? I've found nothing to support that, aside from 'cutaneous
respiration' papers that ignore eccrine sweating.
I expected to find some papers on it, but not much:

Carbon dioxide emission from human skin was measured with a Luft Infrared
Analyzer Emission rate was 3.4 times 10-5 ml CO2/cm2/min for the arm and forearm
combined 4.6 times 10-5 ml CO2/cm2/min for the hand only, and 1.8 times 10-5 ml
CO2/cm2/min for the forearm only. Emission rate of the arm and forearm increased
to 8.6 times 10-5 CO2/cm2/min after vigorous exercise, and 9.1 times 10-5 ml
CO2/cm2/min after wetting the skin.

# Fitzgerald, LE: Cutaneous respiration in man. Physiol. Rev 1957 37: 325, |
PubMed | ISI | ChemPort |
# Petrun, NM: The effects of increased oxygen, carbon dioxide, and nitrogen
partial pressures on cutaneous respiration in man. Neklady Akad. Nauk SSSR.
(Biol. Sci. Sect. Transl.) 1958 118: 1/6 108,
# Klocke, RA, Gurtner, GH, Farhi, LE: Gas transfer across the skin in man. J.
Appl. Physiol 1963 13: 311,
# Adamcyzk, B, Boerboom, AJH, Kistemaker, J: A mass spectrometer for continuous
analyses of gaseous compounds excreted by human skin. J. Appl. Physiol 1966 21:
6 1903, | PubMed |

http://www.springerlink.com/content/k112t5377665371m/
http://www.highbeam.com/doc/1G1-165268252.html

Why do I feel like a human salt lick after exercising?

That's because sweat is composed primarily of water, potassium and salt (a mix
of sodium and chloride). The ratio of those components varies from person to
person, and your body adjusts that ratio depending on the fluctuation of its
levels of water, potassium and salt.

Sweat glands draw fluid from the bloodstream and pass the water to the surface.
They normally reabsorb salts and recycle them back into the bloodstream. But
during heavy sweating they can't keep up with the flow, and large amounts of
salt slip past them and escape the body.

How many sweat glands do we have?

The average person has 2.6 million sweat glands in the skin.

(foot has 250,000 sweat glands)

DOGS' sweat glands are between their paw pads but they don't use them for
regulating their temperature. If a dog is hot they will pant to cool the blood
in their tongue with saliva

http://ajplegacy.physiology.org/cgi/pdf_extract/95/1/13

http://jp.physoc.org/cgi/content/full/538/3/985


http://books.google.com/books?id=LKy0weDEFp8C&pg=PA887&lpg=PA887&dq=eccrine+swea\
t+salt+recycle&source=bl&ots=4YrhDv8M4L&sig=RIIVCDps8CzSOqrayMvAQo5Udv4&hl=en&ei\
=pt_hSa33IYWytgPW_ZWpCQ&sa=X&oi=book_result&ct=result&resnum=9#PPA887,M1

Sweat glands normally reabsorb salts and recycle them back into the bloodstream.

CFTR expression was detected at the luminal surface of reabsorptive sweat ducts
and airway submucosal glands, at the apex of ciliated cells in pseudostratified
respiratory epithelia and of isolated cells of the villi of duodenum and
jejunum, and within intracellular compartments of intestinal goblet cells.

THE SECRETORY PORTION of the eccrine sweat gland generates a fluid called the
primary secretion. The composition of this isotonic fluid is similar to an
ultrafiltrate of the plasma and has a pH of 7.4. However, as it flows through
the ductal portion of the gland, this fluid is modified by the reabsorption of
solutes such as Na+, Cl-, lactate, and
HCO<UP><SUB>3</SUB><SUP>&#8722;</SUP></UP>, leaving a hypotonic sweat (4, 32).
Current models of ionic transport in the human eccrine sweat duct propose the
presence of luminally located Na+ and Cl- channels and basolaterally located
Na+-K+-ATPase, as well as K+ and Cl- 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). The acidity of sweat
implies that sweat duct cells secrete protons across the apical membrane, and
the presence of an electrogenic proton-secreting pump at this membrane has been
proposed (3, 27, 34). Indeed, vacuolar-type H+-ATPases (V-ATPases) have been
shown to be responsible for the acidification in many organelles of eukaryotic
cells, including clathrin-coated vesicles, lysosomes, endosomes, and vacuoles of
plants and fungi (31). Moreover, V-ATPases are highly expressed in the apical
membrane of specialized epithelial cells in the kidney (13, 24), epididymis, and
vas deferens (14), where they play a major role in the acidification of urine
and luminal fluid of the reproductive tract (11, 16, 12, 23).