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)
Kenney
W L
WL
Laboratory for Human Performance Research, Pennsylvania State University, University Park 16802.
Fowler
S R
SR
D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D002794:Choline / Q000031:analogs & derivatives* / Q000494:pharmacology; D004439:Eccrine Glands / Q000033:anatomy & histology / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D013542:Sweat / Q000187:drug effects / Q000378:metabolism; D013545:Sweat Glands / Q000187:drug effects*
C017506:methylcholine; D002794:Choline