Adaptive sweat gland response after spinal cord injury.

Abstract

To compare the eccrine gland cholinergic sensitivity of upper (UE) and lower (LE) extremities in untrained able-bodied individuals (UAB), untrained individuals with spinal cord injury (U/SCI), and trained wheelchair athletes (E/SCI). Static group comparison. SCI population. A total of 25 men (mean age, 27.8+/-5.0 y; mean height, 175.8+/-9.1cm; mean weight, 76.2+/-7.7 kg) were categorized into 3 groups UAB (n=10), U/SCI (n=10), and E/SCI (n=5). Individuals with SCI had injuries ranging from C4-8. Peripheral sweat production was induced by using pilocarpine iontophoresis at surface landmarks relative to the flexor carpi radialis and medial gastrocnemius muscles. Peripheral sweat rate (SR), sweat gland density (SGD), and sweat per gland (S/G) were calculated for both UE and LE. Peripheral SR for the UAB in both UE (7.58+/-1.99 g x m(-2) x min(-1)) and LE (4.42+/-1.23 g x m(-2) x min(-1)) were significantly greater than those for U/SCI (1.08+/-1.01 g x m(-2) x min(-1), .24+/-.35 g x m(-2) x min(-1), respectively) and E/SCI (3.61+/-2.1 g x m(-2) x min(-1),.71+/-.81 g x m(-2). min(-1), respectively). Furthermore, the UE versus LE SR ratio was calculated at 1.71:1 for UAB subjects, whereas U/SCI and E/SCI subjects showed a ratio of 4.50:1 and 5.07:1, respectively. UE SGD measures in U/SCI (83.20+/-39.84 glands/cm(2)) persons were significantly less than either the UAB (120.20+/-21.42 glands/cm(2)) or the E/SCI (120.80+/-21.56 glands/cm(2)). These results may indicate that sweat glands below the lesion are less sensitive to cholinergic activation, regardless of central or exogenous stimulation. However, glands above the level of the lesion may exhibit increased productivity when individuals are exposed to physical training and physiologic stress.