Effects of three days of dry immersion on heart rate and blood pressure variabilities during head-up tilting in humans.
In this study we examined the effects of 3 days of dry immersion on heart rate variability (HRV) and blood pressure variability (BPV) in response to head-up tilting in 4 healthy young subjects aged 21 to 36 years. Resting value of the high-frequency (HF) power of BPV and HRV decreased, while the low-frequency (LF)/HF ratio of HRV and blood pressure increased after the dry immersion. The HF power of HRV decreased, while the LF/HF ratio of HRV and heart rate increased during head-up tilting before and after dry immersion. All powers of BPV and BP were unchanged during head-up tilting. The values of the decrease in the HF power of HRV and the increase in the LF/HF ratio during head-up tilting after dry immersion were larger than those before. These results suggest that 3 days of dry immersion altered the autonomic balance toward the sympathetic dominant at rest, and that cardiac function may play a crucial role in BP maintenance during head-up tilting compared with vasoconstrictor function.
Miwa
C
C
Department of Autonomic Neuroscience, Nagoya University, Japan.
Sugiyama
Y
Y
Iwase
S
S
Mano
T
T
Ohira
Y
Y
Grigoriev
A
A
Kozlovskaya
I
I
Egorov
A
A
Shenkman
B
B
D000328:Adult; D001794:Blood Pressure / Q000502:physiology*; D018493:Cardiovascular Deconditioning / Q000502:physiology*; D004562:Electrocardiography; D018475:Head-Down Tilt; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D007024:Hypotension, Orthostatic / Q000209:etiology*; D007101:Immersion; D008297:Male; D011187:Posture / Q000502:physiology; D018474:Weightlessness Simulation