Methylcholine-activated eccrine sweat gland density and output as a function of age

The purpose of this investigation was to examine eccrine sweat gland responsiveness to intradermal injections of methylcholine (MCh) across three age groups of men [young (Y) = 22-24; middle (M) = 33-40; older (O) = 58-67 yr old, n = 5 per group]. Subjects were matched with respect to maximum O2 consumption, body size, and body composition, and were thoroughly heat acclimated before participation. Randomly ordered concentrations of acetyl-beta-methylcholine chloride ranging from 0% (saline) to 0.1% (5 x 10(-3) M) were injected into the skin of the dorsal thigh in a thermoneutral environment, and activated sweat glands were photographed at 30-s intervals for the next 8 min. Density of MCh-activated glands was independent of both age and [MCh] (e.g., 2 min after injection of 5 x 10(-3) M [MCh]: Y = 45 +/- 7, M = 46 +/- 12, O = 42 +/- 5 glands/cm2). However, sweat gland output (SGO) per active gland was significantly lower for the O group and failed to increase with increasing [MCh] above 5 x 10(-4) M. When MCh (5 x 10(-3) M) was injected after 1 h of exercise in the heat, higher SGO's were elicited in each group; however, the SGO of the O group was again significantly lower than that of the Y group (91 +/- 11 vs. 39 +/- 4 ng/gland, P less than 0.02) with the M group intermediate (69 +/- 11 nl/gland; 2 min postinjection data).(ABSTRACT TRUNCATED AT 250 WORDS)

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Morphological Connections of the Human Apocrine and Eccrine Sweat Gland - Occurrence of the So-called "Mixed Sweat Glands" - A Review

Okajimas Folia Anatomica Japonica ◽

10.2535/ofaj1936.65.5_315 ◽

1988 ◽

Vol 65 (5) ◽

pp. 315-335 ◽

Cited By ~ 6

Author(s):

Toshio ITO

Keyword(s):

Sweat Gland ◽

Eccrine Sweat Gland ◽

Sweat Glands ◽

Eccrine Sweat

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Individual variations in structure and function of human eccrine sweat gland

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1983.245.2.r203 ◽

1983 ◽

Vol 245 (2) ◽

pp. R203-R208 ◽

Cited By ~ 29

Author(s):

K. Sato ◽

F. Sato

Keyword(s):

Sweat Gland ◽

Sweat Rate ◽

Unit Length ◽

Secretory Activity ◽

Eccrine Sweat Gland ◽

Sweat Glands ◽

And Function ◽

Eccrine Sweat

The mechanisms underlying variations in perspiration rate at the glandular level are still poorly understood. Human eccrine sweat glands were dissected from the back of 12 adults, cannulated, and stimulated in vitro with methacholine (Mch). The maximal sweat rate and pKA for Mch determined from the dose-response curve for each individual were compared with the anatomic dimensions of the isolated secretory tubules. There was significant correlation between Mch sensitivity (pKA) and the size of the sweat gland, sweat rate per gland, sweat rate per unit length of the secretory tubule, and sweat rate per unit glandular volume. The sweat glands from individuals judged to be poor sweaters exhibited smaller size, lower secretory activity both in vivo and in vitro, and decreased Mch sensitivity compared with glands from physically fit individuals. We conclude that the increased Mch sensitivity and glandular hypertrophy are the two important features of functionally active sweat glands and infer that these parameters could improve as a result of acclimatization to physical exercise and/or heat.

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Sweat secretion by human axillary apoeccrine sweat gland in vitro

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1987.252.1.r181 ◽

1987 ◽

Vol 252 (1) ◽

pp. R181-R187 ◽

Cited By ~ 6

Author(s):

K. Sato ◽

F. Sato

Keyword(s):

Sweat Gland ◽

Sweat Rate ◽

Fluid Secretion ◽

Eccrine Sweat Gland ◽

Sweat Glands ◽

Clear Fluid ◽

Apocrine Glands ◽

Sweat Secretion ◽

Eccrine Sweat

Functional characteristics of isolated single human axillary apoeccrine sweat glands have been studied using in vitro sweat induction methods. Sustained copious clear fluid secretion was evoked by methacholine (MCh), epinephrine (EP), isoproterenol (ISO), and phenylephrine (PL) in decreasing order in a pharmacologically specific manner. Apoeccrine glands showed a higher cholinergic sensitivity than eccrine sweat glands, as shown by the apparent association constant for MCh of 2.7 X 10(-7) M compared with 2.1 X 10(-6) M for the axillary eccrine sweat gland. The average total sweat rate of the apoeccrine gland for a 30-min period was sevenfold higher than that of the eccrine sweat gland. In contrast, isolated apocrine glands showed intermittent pulsatile turbid sweat secretion in response to MCh or EP. The Na+ and K+ concentration of apoeccrine glands was nearly isotonic, whereas those of apocrine sweat was 120-140 mM for Na+ and 10-20 mM for K+. Apoeccrine ductal Na+ absorption was also observed in the apoeccrine glands and was no more efficient than that of the axillary eccrine sweat gland. Thus apoeccrine sweat glands are functionally and pharmacologically distinct from axillary apocrine glands and significantly contribute to overall axillary sweating in humans.

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