{'fraction_non_alphanumeric': 0.02981651376146789, 'fraction_numerical': 0.010703363914373088, 'mean_word_length': 5.088372093023255, 'pattern_counts': {'":': 0, '<': 1, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Attenuated increases in sweat rate but not skin blood flow to increasing doses of methacholine in aged skin

Sweating and skin blood flow responses to whole‐body heat stress are decreased in aged skin. This study tested the hypothesis that these responses are attenuated to exogenous methacholine (MCh) in aged skin. Two microdialysis membranes were placed in dorsal forearm and lower leg skin in 7 healthy young (22±1) and elderly (63±2) subjects. Local sweat rate (SR) and skin blood flow were simultaneously measured over each microdialysis membrane. After insertion trauma subsided, and while skin temperature was clamped at 34°C, progressively increasing doses of MCh were administered (5 min/dose). Cutaneous vascular conductance (CVC) was not different between groups prior to and across all doses of MCh regardless of site, although forearm CVC was greater relative to lower leg CVC in both groups (both P<0.001). On the other hand, SR in aged skin was lower relative to young skin (significant dose × age interaction), while there was no regional difference between leg and arm responses in either group. These results confirm prior findings that sweat gland function is reduced in aged skin. Conversely, there is no effect of aging on cutaneous vasodilator responsiveness to exogenous methacholine.