Objective To explore the dynamic changes and significance of heart rate variability(HRV)during the initial phase after acute exposure to Tibet plateau by combining time,frequency domain and non-linear analysis.Methods Eighty-six healthy young men of Han nationality underwent short-term(5 min)heart rate variability(HRV)monitoring at 560 meter above sea level(plain),then were transported to Tibet plateau(3675-meter above sea level)by airplane.There,all subjects were divided into 3 groups,and A gorup(n=12)underwent HRV monitoring on the 2nd day after arrival,B group(n=48)on the 3rd day,C group(n=26)on the 4th day.Results Compared with the data obtained at plain,the standard deviation of normal to normal intervals(SDNN),high frequency(HF)and total power(TP)decreased significantly(P50 ms(PNN50)and normalized high frequency(HFnu)also decreased obviously(P

To evaluate the effect of aerobic and anaerobic endurance training the regulating the function of autonomic nervous system, in order to provide scientific basis for optimizing the project of physical fitness training. Fourty-one healthy young men were randomly divided into aerobic and anaerobic endurance training groups. The training period was 8 weeks. Pre-exercise, 4 weeks and 8 weeks after trained, HRV were measured compared with pre-exercise. The autonomic balance in aerobic endurance group had an increasing parasympathetic activity (HF, HFnu, RMSSD, PNN50, all P was < 0.05) and relatively decreasing sympathetic activity (LFnu). This group showed a parasympathetic predominance (LF/HF) and increase of HRV. While in the anaerobic group there was a relative stabilization with the function of autonomic nervous system. The present study shows that the effect of aerobic and anaerobic endurance training on the autonomic nervous system depends on its intensity. Proper intensity of anaerobic endurance training may be beneficial to improve the adaptability of human body for circumstances as aerobic endurance training.
Adolescent ; Adult ; Autonomic Nervous System ; physiology ; Electrocardiography ; Exercise ; physiology ; Heart Rate ; physiology ; Humans ; Male ; Physical Endurance ; physiology ; Running ; physiology ; Sympathetic Nervous System ; physiology ; Vagus Nerve ; physiology

The characteristics of cardiovascular autonomic nerve system(ANS) modulation during exposure to three different altitudes were compared by time domain, spectral and nonlinear analysis of short-(5 minutes)term heart rate variability (HRV). The standard deviation of all RR intervals (SDNN), the square root of the mean squared differences of successive RR intervals (rMSSD), the percentage of successive interval differences >50 ms (PNN50), low frequency (LF), high frequency power (HF), and total power (TP) at 2800 m were slightly higher than those at 1856 m, but the differences were non-significant statistically. SDNN, rMSSD, LF and HF at 3040 m were significantly lower than those at 1856 m and 2800 m. These results show that parasympathetic nerve activity decreases significantly, and ANS modulation is blunted after exposure to higher altitude. This kind of change of ANS may contribute to further elucidate pathophysiology in body after exposure to high altitude.
Adult ; Altitude ; Autonomic Nervous System ; physiology ; Electrocardiography ; Heart Rate ; physiology ; Humans ; Male

[Objective] In view of the crucial role of indole propionic acid in the treatment of tumor immune checkpoint blockade and further revealing its mechanism, our study intended to design and synthesize 1-[¹⁸F]-fluoroethyl-indole propionic acid (1-[¹⁸F]-IPA), and evaluate it as a tumor PET imaging agent. [Methods] The precursor 1-(2-p-toluenesulfonic acid oxygen ethyl)-methyl indole propionate underwent nucleophilic substitution reaction with ¹⁸F^-. The crude product was separated and purified by high-performance liquid chromatography and the intermediates were collected. Finally, 1-[¹⁸F]-IPA was obtained by hydrolysis. The clarity of the product was measured by visual inspection, the pH value was determined by precision test paper, and the radiochemical purity and stability were determined by high-performance liquid chromatography. In order to determine the biodistribution of 1-[¹⁸F]-IPA in normal mice, ICR mice were intravenously injected with 1-[¹⁸F]-IPA (0.2 mL, 7 MBq), and sacrificed at 5, 15, 25, 45, 75 and 120 min and dissected. Micro-PET imaging was performed and analyzed in BxPC-3 tumor-bearing nude mice. Student t test was used to compare the biodistribution of tissues and organs at different time points. [Results] The total preparation time of 1-[¹⁸F]-IPA was 35-40 min, the radiochemical yield was (45±5)%, and the radiochemical purity was more than 95%. The product solution was clear without particles, and the pH value was 6.5, which had good stability in vitro and in vivo. The results of biodistribution in healthy ICR mice showed that except for the brain, 1-[¹⁸F]-IPA had a certain uptake in all major organs, with the most obvious uptake in the liver, gallbladder and kidneys. The radioactivity in the gallbladder gradually increased with time and reached (39.86±6.56)%ID/g at 120 min, but bone uptake did not change significantly with time. Micro-PET/CT showed that there was radioactive uptake at the tumor 30 min after injection of 1-[¹⁸F]-IPA in Dutch BxPC-3 nude mice, but it was not obvious. At this time, SUVmax was about 55.18±14.62. Consistent with the results of biodistribution, the brain uptake was low at each time point. [Conclusion] In summary, 1-[¹⁸F]-IPA with short preparation time and high yield is expected to be a tool to probe tryptophan indole metabolism pathway and further reveal tumor immune resistance.