Relationships between transepidermal water loss, cutaneous microcirculatory function and autonomic nervous activity

Several studies have shown that a deterioration of skin properties, an impaired cutaneous microcirculatory function and an imbalance of autonomic nervous activity are observed in smokers and in patients with diabetes mellitus or Raynaud's phenomenon. These observations suggest that skin properties are associated with cutaneous microcirculatory function and autonomic nervous activity in pathological conditions. However, there is no published evidence to support the concept that these two functions have any relationship with skin properties even in healthy subjects. To investigate the hypothesis that these properties are related, we conducted a survey of healthy adult subjects to investigate the relationships between cutaneous microcirculatory function and autonomic nervous activity and skin properties.

The hydration of the stratum corneum and transepidermal water loss (TEWL) were investigated as skin properties, and the responsiveness of skin blood flow (SkBF) to local warming was examined as an index of cutaneous microcirculatory function in 19 healthy adult male subjects. Electrocardiograms were monitored for 24 h and heart rate variability was analysed considering low-frequency power (LF: 0.04-0.15 Hz), high-frequency power (HF: 0.15-0.40 Hz) and a ratio of low- to high-frequency power (LF/HF) as indices of autonomic nervous activity; HF is an index of parasympathetic activity, whereas LF/HF is an index of sympathovagal balance. The relationships between those indices were then analysed.

A moderate negative correlation was found between TEWL and the relative maximum rate of increases in the responsiveness of SkBF on local warming. A moderate positive and a moderate negative correlation were observed between TEWL and LF/HF or HF, respectively. Moreover, a moderate negative and a moderate positive correlation were shown between the responsiveness of SkBF and LF/HF or HF, respectively. The hydration of the stratum corneum showed no correlations with any indices of microcirculation or autonomic nervous activity.

These results indicate that skin barrier function, cutaneous microcirculatory function and autonomic nervous activity are mutually associated in healthy adults.