Search

Background Eccrine sweat secretion is of central importance for control of body temperature. Although the incidence of sweat gland dysfunction might appear of minor importance, it can be a real concern for people with either hypohidrosis or hyperhidrosis. However, sweat gland function remains relatively poorly explored. Objectives To investigate the function of single human sweat glands. Methods We describe a new approach for noninvasive imaging of single sweat gland activity in human palms in vivo up to a depth of 100 μm, based on nonlinear two-photon excited autofluorescence ( TPEF) and coherent anti-Stokes Raman scattering ( CARS). Results These techniques appear to be useful compared with approaches already described for imaging single sweat gland activity, as they allow better three-dimensional spatial resolution of sweat pore inner morphology and real-time monitoring of individual sweat events. By filling the sweat pore with oil and tuning the CARS contrast at 2845 cm−1, we imaged the ejection of sweat droplets from a single sweat gland when oil is pushed out by sweat flow. On average, sweat events lasted for about 30 s every 3 min under the conditions studied. On the other hand, about 20% of sweat glands were found inactive. TPEF and CARS were also used to study, at the single pore level, the antiperspirant action of aluminium chlorohydrate ( ACH) and to reveal, for the first time in vivo, the formation of a plug at the pore entrance, in agreement with reported ACH antiperspirant mechanisms. Conclusions Although data were acquired on human palms, these techniques show great promise for a better understanding of sweat secretion physiology and should be helpful to improve the efficacy of antiperspirant formulations. [ABSTRACT FROM AUTHOR]