健康・身体活動を支える交感神経の活動

This paper reviews findings in humans regarding sympathetic nervous activity in homeostatic regulatory control in healthy life and physical activity. Data from microneurography recordings of sympathetic nerve activity to skeletal muscle vasculature (MSNA: muscle sympathetic nerve activity), the neural activity influences that cardiovascular system suitably control arterial blood pressure and blood flow at rest and during exercise. Resting MSNA strength is different depending on age, sex, body mass index (BMI), heredity, and various stressors such as environmental stress, e.g., gravity, ambient temperature, and inactivity or mental stressors. For instance, in condition changing the posture from supine to standing position, MSNA strength heightened strongly to prevent orthostatic hypotension. In exercise challenges, it is necessary to maintain homeostasis by cardiovascular, metabolic, and thermoregulatory adjustments, by specific changes in sympathetic nerve activity. Although the strength of MSNA during exercise increases in relation to the exercise intensities and durations, MSNA activities decrease temporally when blood pressure is too high. Additionally, MSNA response to exercise can be modified with changes in exercise mode, exercise position, skeletal muscle fatigue, and body temperature. Observations of the MSNA responses in activities of daily life showed that sympathetic function for homeostatic regulatory control is essential in healthy life. In addition, this suggests that the sympathetic function can be maintained with an active lifestyle. It can be concluded that daily activity plays a key role to sustain the sympathetic neural regulation in homeostatic function and support health and wellbeing.