Establishment and evaluation of an experimental rat model for high-altitude intestinal barrier injury.

In the present study an experimental high-altitude intestinal barrier injury rat model was established by simulating an acute hypoxia environment, to provide an experimental basis to assess the pathogenesis, prevention and treatment of altitude sickness. A total of 70 healthy male Sprague-Dawley rats were divided into two groups: Control group (group C) and a high-altitude hypoxia group (group H). Following 2 days adaptation, the rats in group H were exposed to a simulated 4,000-m, high-altitude hypoxia environment for 3 days to establish the experimental model. To evaluate the model, bacterial translocation, serum lipopolysaccharide level, pathomorphology, ultrastructure and protein expression in rats were assessed. The results indicate that, compared with group C, the rate of bacterial translocation and the apoptotic index of intestinal epithelial cells were significantly higher in group H (P<0.01). Using a light microscope it was determined that the intestinal mucosa was thinner in group H, there were fewer epithelial cells present and the morphology was irregular. Observations with an electron microscope indicated that the intestinal epithelial cells in group H were injured, the spaces among intestinal villi were wider, the tight junctions among cells were open and lanthanum nitrate granules (from the fixing solution) had diffused into the intestinal mesenchyme. The expression of the tight junction protein occludin was also decreased in group H. Therefore, the methods applied in the present study enabled the establishment of a stable, high-altitude intestinal barrier injury model in rats.

[The deacclimatization symptom scores of 159 youth returning to the same plain from different plateau].

OBJECTIVE: To analysis deacclimatization symptom scores of 159 youth from Karakoram and Tibet Ali area, and provide the basis for the development of relevant prevention and control measures. METHODS: Using the method of epidemiological symptoms questionnaire, 18 symptoms of 190 youth who returned to the plain area from the different plateau were investigated. The symptom scores of different altitude, age, the time of staying, different units, continuous or intermittent stage and education were surveyed. RESULTS: Deacclimatization symptom scores among 5,000 meter groups were significantly higher than those of 4,300 meter and 3,700 meter group (P < 0.05, P < 0.01). There was no significant difference between the 4,300 meter group and the 3,700 meter group (P > 0.05). There were significant differences among the stayed personnel (different age, position, unit, education, time, continuous or intermittent) (P < 0.01). There was significant difference between the continuous defended the group and intermittent group (P < 0.01). CONCLUSION: Deacclimatization symptom scores were related to the plateau exposure time, altitude, workload, plateau continued exposure. The older, the longer exposure, the higher altitude, the greater workload at plateau were showed higher deacclimatization symptom score.

Amphipathicity and self-assembly behavior of amphiphilic alginate esters.

Amphiphilic alginate esters (Alg-C(n)) with different degree of substitution (DS) and hydrophobic alkyl length were synthesized by the reaction between partially protonated sodium alginate and aliphatic alcohols (octanol, dodecanol or hexadecanol) and characterized by conventional methods. The critical micelles concentration (CMC) of Alg-C(n) was determined by measuring the fluorescence intensity of pyrene as a fluorescent probe, conductance and surface tension (SFT). Formation and characteristics of the self-assembly micelles of Alg-C(n) were studied by transmission electron microscopy (TEM) and Zetasizer Nano Series method. The results indicate that CMC value and the self-assembled micelle size decreased with the increasing of the hydrophobic alkyl chain length, as the DS of Alg-C(n) is similar.

[Relationship of high altitude de-adaptation with acute high altitude response and cardiac function].

OBJECTIVE: To assess the relationship of high altitude de-adaptation response (HADAR) with acute high altitude response (AHAR) and cardiac function. METHODS: Ninety-six military personnel of rapid entering into high altitude (3 700 to 4 800 m) with strong physical work were analyzed, all subjects were male, aged 18 - 35 years. According to the symptomatic scores of AHAR were divided into 3 groups: sever AHAR (group A, 24), mild to moderate AHAR (group B, 47) and non-AHAR (group C, 25) at high altitude. According to the symptomatic scores of HADAR were divided into 3 groups: severe HADAR (group E, 19), mild to moderate HADAR (group F, 40) and non-HADAR (group G, 37) after return to lower altitude (1 500 m). Mean pulmonary arterial pressure (mPAP), right ventricular internal dimension (RVID), outflow tract of right ventricle (RVOT), left ventricular internal dimension (LVID), left ventricular ejection fraction (LVEF), cardiac muscle work index (Tei index), creatine kinase isoenzymes-MB (CK-MB), lactic dehydrogenase isoenzyme-1 (LDH-1) were measured at high altitude stayed 50 days and after return to lower altitude 12 h, 15 d, and 30 d. Fifty healthy volunteers (group D) at 1 500 m altitude served as control. RESULTS: Level of mPAP, RVID, RVOT, RVID/LVID ratio, Tei index, CK-MB,and LDH-1 were higher, and LVEF was lower in group A than those in group B, C and D, there were significant differences between group B and C, C and D (all P < 0.01). AHAR scores were positively correlated with HADAR scores (r = 0.863, P < 0.01). Twelve hours after return to lower altitude, level of mPAP, RVID, RVOT, RVI/LVID ratio, Tei index, CK-MB, and LDH-1 were higher, and LVEF was lower in group E than those in group F, G and D, there were significant differences between group F and G, G and D (all P < 0.01). Fifteen days after return to lower altitude, level of mPAP, RVID, RVOT, RVID/LVID ratio were higher in group E than those in group F, G, and D, there were significant differences between group F and G, and D (P < 0.01 or P < 0.05), there were no significant differences between group G and D (all P > 0.05), LVEF, Tei index, CK-MB, LDH-1 showed no significant differences among groups (all P > 0.05). Thirty days after return to lower altitude, these parameters in group E, F, and G showed no significantly differences compared with those of group D (all P > 0.05). CONCLUSION: The severity of HADAR is associated with severity of AHAR and cardiac injury, the more serious of AHAR and cardiac injury at high altitude, the more serious of HADAR and cardiac injury after return to lower altitude, the more long of restore of right cardiac morphologic injury.

Therapeutic intervention against deacclimatization to high altitude.

The incidence of deacclimatization to high altitude syndrome (DAHAS) prevailed up to 80% in highland troops, and 100% in manual workers, and severe DAHAS could significantly affects patients' health, work and life. So it is imperative to develop effective prevention and treatment measures for DAHAS. The present review analyzes effective prophylactic and therapeutic measures against DAHAS, implemented at our hospital.

[The role of hypoxia inducible factor-1α and vascular endothelial growth factor in hypoxic pulmonary hypertension in patients with acute high altitude reaction of rescue workers in Yushu earthquake].

OBJECTIVE: To assess the effects of hypoxia inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) on hypoxic pulmonary hypertension(HPH) in patients with acute high altitude reaction(AHAR) and its change after return to lower altitude. METHODS: Ninety-six officers and soldier participating in rescue of Yushu megaseism on April 14th in 2010, leaving low altitude area (1 500 m) rapidly to high altitude area(3 700 m) to undertake strenuous physical work were enrolled for study. All of them were male, aged 18-35 years, and they were divided into three groups according to the symptomatic scores of AHAR: without AHAR(group B, n=25), mild to moderate AHAR (group C, n=47 ) and severe AHAR (group D, n=24). Mean pulmonary artery pressure (mPAP), levels in serum HIF-1α and VEGF were measured at high altitude area after a stay of 50 days, and also after their return to lower altitude area (1 500 m) for 12 hours and 15 days. Fifty healthy volunteers at low altitude area served as control (group A). RESULTS: Level of mPAP (mm Hg, 1 mm Hg=0.133 kPa), serum HIF-1α (pg/L) and VEGF (ng/L) in group B (24.23±1.56, 68.80±7.52 and 82.56±6.32) were significantly higher than those in group A (18.50±1.30, 50.95±3.33 and 65.78±4.03), respectively (all P<0.01). Moreover, the value of all the parameters increased with increase in severity of AHAR, the respective value in group C were 28.42±1.32, 88.10±9.20 and 104.82±10.36, and in group D were 34.70±2.94, 117.93±13.46 and 136.77±12.03, and there were significant differences in comparing two groups (all P<0.01). At high altitude area, AHAR total score was positively correlated with mPAP, serum HIF-1α and VEGF (r=0.672, 0.737 and 0.634, respectively, all P<0.01), mPAP was positively correlated with serum HIF-1α and VEGF (r=0.706, 0.638, both P<0.01). Compared with group A, level of mPAP (29.08±4.22), serum HIF-1α (91.16±20.58) and VEGF (107.11±10.32) were significantly increased in 96 officers and soldiers who stayed for 50 days at an altitude of 3 700 m (all P<0.01), and the values were significantly decreased after returning to lower altitude area for 12 hours(23.05±3.18, 70.99±8.22 and 78.65±6.47) and 15 days(18.96±1.75, 52.31±4.92 and 63.08±4.55). The values showed significant difference between 12 hours and 15 days stay at 1 500 m (all P<0.01). The values of the determined parameters 15 days after return to lower altitude area showed no difference compared with those of group A (all P>0.05). CONCLUSION: Strenuous physical work at high altitude area, AHAR becomes more serious, and it is accompanied by higher values of HIF-1α, VEGF and mPAP, indicating that HPH is closely associated with elevation of HIF-1α and VEGF. These changes are improved after returning to lower altitude area for 12 hours, and they recover to normal lever after 15 days.

Over-starvation aggravates intestinal injury and promotes bacterial and endotoxin translocation under high-altitude hypoxic environment.

AIM: To study whether over-starvation aggravates intestinal mucosal injury and promotes bacterial and endotoxin translocation in a high-altitude hypoxic environment. METHODS: Sprague-Dawley rats were exposed to hypobaric hypoxia at a simulated altitude of 7000 m for 72 h. Lanthanum nitrate was used as a tracer to detect intestinal injury. Epithelial apoptosis was observed with terminal deoxynucleotidyl transferase dUTP nick end labeling staining. Serum levels of diamino oxidase (DAO), malondialdehyde (MDA), glutamine (Gln), superoxide dismutase (SOD) and endotoxin were measured in intestinal mucosa. Bacterial translocation was detected in blood culture and intestinal homogenates. In addition, rats were given Gln intragastrically to observe its protective effect on intestinal injury. RESULTS: Apoptotic epithelial cells, exfoliated villi and inflammatory cells in intestine were increased with edema in the lamina propria accompanying effusion of red blood cells. Lanthanum particles were found in the intercellular space and intracellular compartment. Bacterial translocation to mesenteric lymph nodes (MLN) and spleen was evident. The serum endotoxin, DAO and MDA levels were significantly higher while the serum SOD, DAO and Gln levels were lower in intestine (P < 0.05). The bacterial translocation number was lower in the high altitude hypoxic group than in the high altitude starvation group (0.47 ± 0.83 vs 2.38 ± 1.45, P < 0.05). The bacterial translocation was found in each organ, especially in MLN and spleen but not in peripheral blood. The bacterial and endotoxin translocations were both markedly improved in rats after treatment with Gln. CONCLUSION: High-altitude hypoxia and starvation cause severe intestinal mucosal injury and increase bacterial and endotoxin translocation, which can be treated with Gln.

[Three preparations of compound Chinese herbal medicines for de-adaptation to high altitude: a randomized, placebo-controlled trial].

BACKGROUND: With the increase of troops entering the plateau for a variety of missions, the occurrence of de-adaptation increased significantly when the army returned to the plains, however, until now, there has been no effective treatment for de-adaptation to high altitude. OBJECTIVE: To observe the interventional effects of compound Chinese herbal preparations (Sankang Capsule, Rhodiola Rosea Capsule and Shenqi Pollen Capsule) on de-adaptation to high altitude, and provide scientific evidence for appropriate treatment methods in the army health care for future missions. DESIGN, SETTING, PARTICIPANTS AND INTERVENTIONS: A randomized, single-blind, placebo-controlled trial design was used. Soldiers of a returning army unit who exhibited de-adaptation response symptoms were selected for observation after participating in earthquake relief at high altitude. A total of 543 soldiers were divided into a Sankang Capsule group, a Rhodiola Rosea Capsule group, a Shenqi Pollen Capsule group and a placebo group for drug intervention and administered with corresponding drugs. The course of treatment was 15 days. A self-evaluation scale for de-adaptation to high altitude was used to measure the signs and symptoms exhibited by the soldiers. MAIN OUTCOME MEASURES: Effective rate of signs and symptoms of de-adaptation to high altitude was analyzed after a 15-day treatment and the differences of improvement rate of symptoms between groups were compared to evaluate the efficacy of the drugs. RESULTS: All three drugs improved the symptoms of de-adaptation to high altitude. Compared with the placebo group, symptoms of de-adaptation to high altitude in the drug-treated groups were remitted (P<0.05). Compared with placebo, Sankang Capsule mainly had well-marked effects on dizziness, fatigue, palpitations, cough, sputum and sore throat (P<0.05); Rhodiola Rosea Capsule significantly reduced the symptoms of fatigue, drowsiness, chest tightness, palpitations, vertigo, lack of attention and memory loss (P<0.05); Shenqi Pollen Capsule significantly reduced the symptoms of dizziness, fatigue, weakness, chest tightness, palpitations, cough, sputum, sore throat, memory loss, unresponsiveness and limb numbness (P<0.05). The symptom improvement rate of Shenqi Pollen Capsule was significantly higher than those of the other two drugs. CONCLUSION: All the three drugs played an evident role in ameliorating symptoms of de-adaptation, and the use of Shenqi Pollen Capsule was more effective than Rhodiola Rosea Capsule and Sankang Capsule.

[Effect of oxidative stress in development of acute high altitude response during the process of strong physical work at high altitude].

OBJECTIVE: To assess the effect of oxidative stress in development of acute high altitude response (AHAR) during the process of strong physical work at high altitude and its change after return to lower altitude. METHODS: Ninety-six officers and soldiers of rapid entering into high altitude (3 700 m) with strong physical work were analyzed, all subjects were male, aged 18-35 years. According to the symptomatic scores of AHAR were divided into 3 groups: severe AHAR (group A, n = 24), mild AHAR (group B, n = 47) and without AHAR (group C, n = 25). Levels in serum 8-iso prostaglandinF2alpha(8-iso-PGF2alpha), superoxide dismutase (SOD) and malonaldehyde (MDA) were measured at higher altitude stayed 50 d and after return to lower altitude (1 500 m) 12 h and 15 d, and 50 healthy volunteers (group D) at 1 500 m altitude served as controll. RESULTS: Levels of serum 8-iso-PGF2alpha and MDA [(9.53 +/- 0.47) microg/L, (8.91 +/- 0.39) micromol/L] were significantly higher in group A than those in group B [(8.34 +/- 0.42) microg/L, (7.31 +/- 0.32) micromol/L] , group C [(7.02 +/- 0.48) microg/L, (6.41 +/- 0.23) micromol/L] and group D [(5.13 +/- 0.56) microg/L, (5.48 +/- 0.33) micromol/L], (all P < 0.01), and serum SOD [(52.08 +/- 3.44) micro/ml] was significantly lower in group A than that in group B [62.27 +/- 2.54) micro/ml], group C [(71.99 +/- 3.35) micro/ml] and group D [(80.78 +/- 3.44) micro/ ml] (all P < 0.01), there were significant differences between group B and C, C and D (all P < 0.01). At altitude 3 700 m 50 d, AHAR scores was positively correlated with serum 8-iso-PGF2alpha and MDA (all P < 0.01), negatively correlated with SOD (P < 0.01). Serum 8-iso-PGF2alpha and MDA were negatively correlated with SOD (all P < 0.01). Levels of serum 8-iso-PGF2alpha and MDA were significantly higher at altitude of 3 700 m 50 d than those at altitude of 1 500 m 12 h,15 d in group D (all P < 0.01), and serum SOD was significantly lower than that at 1 500 m 12 h,15 d in group D (all P < 0.01), there were significantly difference between at 1 500 m 12 h and 15 d (all P < 0.01), there were no difference between at 15 d in group D (all P > 0.05). CONCLUSION: The more serious of oxidative stress and oxidative/antioxidative imbalance, the more serious of AHAR, oxidative stress and oxidative/antioxidative imbalance may be involved in the development of AHAR. The changes were obviously improved after return to lower altitude 12 h, and recovered to normal after 15 d.

[Gastrointestinal dysfunction in acute severe mountain sickness and its relation with multiple organ dysfunction syndrome].

OBJECTIVE: To investigate the relationship between gastrointestinal dysfunction (GD) and multiple organ dysfunction syndrome (MODS) in acute severe mountain sickness (ASMS), including high altitude pulmonary edema (HAPE), and high altitude cerebral edema (HACE), by a retrospective study of medical records and prospective study of hospitalized patients. METHODS: In retrospective study, the clinical data of 3 184 inpatients of General Hospital of Tibetan Military Command suffering from ASMS in the past 50 years (from June, 1958 to June, 2007) were collected. Statistical analysis was performed to study the relationship between GD and MODS in these patients. For the prospective study, 10 admitted patients of ASMS were included. Gastroscopic examination was performed for the ASMS patients, and gastric and duodenal mucosa was scrutinized. At the same time, 30 g of glutamine (Gln) capsule was orally ingested each day for 3 days after the first day of admission. Ten healthy volunteers were included in the control group, and received the same treatment. The levels of serum diamine oxidase (DAO), malonic dialdehyde (MDA), endotoxin and lactulose/mannitol (L/M) ratio were detected before and after treatment in two groups. RESULTS: First, 49.8% of the patients with ASMS were complicated with GD, with 1.5% of fairy stool, and 1.0% with occult blood in stool. In 83 cases of ASMS complicated with MODS, 21.7% (18 cases) appeared GD, and the score of GD was 5.5 in the total score of all organ injury. Second, endoscopic examination showed extensive edema and localized hemorrhage in gastrointestinal mucous membrane, with dotted and patched erosion in gastric antrum and fundus. The pre-treatment DAO, MDA, and endotoxin were higher in the observation group than those in the control group (all P<0.01). After 3 days of Gln capsule treatment, DAO, MDA, and endotoxin were significantly decreased in the observation group (P<0.05 or P<0.01). The pre-treatment L/M ratio in observation group was significantly higher than that in healthy control group (150.69+/-19.91 vs. 117.91+/-17.78, P<0.01). The L/M ratio was significantly decreased after the treatment, as it decreased to 129.37+/-19.75 (P<0.05). However, no significant change in the healthy control group was observed. CONCLUSION: GD plays a major role in the pathogenesis of MODS in ASMS patients.

[Effects of liquids with different osmotic pressure and different oxygen concentration on resuscitation of hemorrhagic shock at high altitude in rat].

OBJECTIVE: To compare the effects of liquids with different osmotic pressure and different oxygen concentration on resuscitation of hemorrhagic shock at high altitude. METHODS: Hemorrhagic shock model of Sprague-Dawley (SD) rats was reproduced by Weigger method at the altitude of 3,658 meters. After 1 hour blood loss, the rats were treated either with normal saline, 75 g/L hypertonic saline solution, 60 g/L dextran 40 solution, solution of 75 g/L hypertonic saline solution with 60 g/L dextran 40, or hypertonic sodium chloride hydroxyethyl starch 40 solution, and all the above solutions were oxygenated with oxygen by high pressure. All the solutions were infused via external jugular vein (4 ml/kg) to resuscitate the rats, and the effects of different solutions on blood pressure (BP), blood gas, intraventricular pressure, water contents of lung or brain, survival time and survival rates were observed. RESULTS: The BP, mean arterial pressure (MAP), partial pressure of oxygen in artery (PaO2), left ventricular systolic pressures (LVSP), maximum upstroke velocity (+dp/dt max) and maximum descending velocity (-dp/dt max) of intraventricular pressure, survival time and survival rate were increased (P<0.05 or P<0.01), but the survival time of the rats in groups treated with hypertonic solutions or hypertonic colloid solutions was obviously prolonged. In particular, survival time and survival rate of the rats in the groups treated with hypertonic colloid solutions were raised more significantly than those of other groups. Besides, the results showed that BP rose steadily in all the groups, PaO2 and LVSP of these groups significantly increased, but partial pressure of carbon dioxide in artery (PaCO2) showed no significant change. Infusion of 4 ml/kg of liquids did not increase water contents of lung or brain. Hyperoxic solutions had no effect on the right ventricular pressure, but the oxygenated liquids could lower the right ventricular pressure at the beginning of resuscitation, suggesting that oxygen transfer through the vein could lower the pulmonary artery pressure and improve the right ventricle function. CONCLUSION: Liquids with different osmotic pressure and at different oxygen concentration showed therapeutical effect on hemorrhagic shock at high altitude in rat, with hypertonic colloid solution being the best among the liquids under examination.

[The clinical significance of leucocytosis and increase in interleukin content in acute mountain sickness complicated with multiple organ dysfunction syndrome].

OBJECTIVE: To study the role of white blood cell (WBC) and interleukins (ILs) in acute mountain sickness (AMS) complicated with multiple organ dysfunction syndrome (MODS). METHODS: Three thousand one hundred and eighty-four patients suffering from severe AMC in the past 50 years were surveyed with questionnaire. Correlation analysis was done to explore the relationship between differential count of WBC and elevation of ILs contents and MODS. RESULTS: There was no difference in differential count of WBC between essential high altitude pulmonary edema (HAPE) and secondary HAPE. No difference was also found between simple HAPE and high altitude cerebral edema (HACE). However, obvious difference in WBC was found between HACE accompanied by HAPE and simple HAPE or simple HACE in the differential counts of WBC, counts of WBC and neutrophil were significantly elevated, while lymphocyte was significantly declined (all P < 0.05). The count of WBC in people suffering from AMS accompanied by MODS was higher than patients only suffering from AMS, lymphocyte was significantly decreased, the difference was obviously (both P < 0.01). The content of tumor necrosis factor-alpha (TNF-alpha), IL-1, IL-2, IL-6 and IL-8 of severe AMS patients were obviously higher than that of normal people, therefore the content of IL-4 in severe AMS patients was obviously lower than that normal people the difference were obvious (all P < 0.01). CONCLUSION: People suffering from AMS also exist systemic inflammatory response syndrome (SIRS). SIRS play an important part in MODS which is a major cause of AMS, and it's a critical factor of high altitude MODS.

[Analysis of 3,184 cases with acute mountain sickness complicated by multiple organ dysfunction syndrome].

OBJECTIVE: To investigate and analyze the probability of acute mountain sickness (AMS) [including high-altitude cerebral edema (HACE) and high-altitude pulmonary edema (HAPE)] complicated by multiple organ dysfunction syndrome (MODS) and its pathogenetic mechanisms. METHODS: Questionnaire survey was made to retrospectively study the hospitalization cases in the past 50 years, and the incidence of high-altitude MODS (H-MODS) were statistically analyzed to determine the main causes and pathogenic mechanism of MODS. RESULTS: Among 3 184 cases with severe AMS, 83 cases conformed to the diagnostic criteria of diagnosis of H-MODS, and the incidence was 2.6%. The pathogenesis of acute H-MODS might be related to the activation of inflammation pathways, activation of blood clotting pathways and the damage to gastrointestinal mucosa barrier. Therefore, improving the diagnosis and the treatment effects of H-MODS is an important measure to increase cure rate of AMS and to decrease its death rate. CONCLUSION: AMS complicated by multiple organ damage (MOD) is the main factor that influences the therapeutic efficacy. Prompt effective remedy on the spot is a significant measure to reduce incidence of MOD.

[Correlation and influences of inflammatory mediators on permeability of the blood-brain barrier at high altitude exposure].

AIM: To investigate the influences of inflammatory mediator on permeability of the blood-brain barrier(BBB) at high altitude environmental exposure as well as relationship and water content in brain. METHODS: Wistar rats were exposed to different altitude gradients, then brain tissue homogenate was prepared, and the activities of tumor necrosis factor-alpha (TNFalpha) and endothelin (ET) in brain tissue homogenate were measured by radioimmunoassay methods. The activities of nitric oxide (NO) in brain tissue homogenate were measured by chemical methods. The evans blue (EB) content in brain tissue was determined by colorimetry and the wet weight/dry weight ratio (W/D) was used to express the water content in brain. RESULTS: With altitude going up, the activities of TNFalpha, NO and ET in the brain of rats rose, and they also rose gradually with time prolonging under high altitude hypoxia exposure. Their most obvious rise was seen during 9 days after ascending 5 000 m high altitude regions. At the same time, the EB and water content in the brain of mice showed the same change trends. Therefore, the inflammatory mediator activity and EB content as well as water content in brain showed an evidently linear relationship. CONCLUSION: The inflammatory mediator plays an important role in the change of permeability of BBB. It's a critical inducing factor in the change of permeability of BBB under high altitude exposure.

[The role of hypoxic response and breath holding at sea level in prediction of acute mountain sickness].

AIM: To explore whether hypoxic response and breath holding at sea level could predict acute mountain sickness (AMS). METHODS: 113 men aged (19 +/- 1) years took part in this study. Blood oxygen saturation (SaO2), heart rate and blood pressure were measured during the course of breathing 10% O2 for 10 minutes and breath holding. Two days later after reaching Lasa (3 658 m altitude) by air, the symptomatic scores of AMS were evaluated. Then the relations between them were analyzed. RESULTS: The SaO2 reduced progressively and the heart rate speeded up, while the blood pressure represented increase at first and then decrease within 10 min during the short-term hypoxia. The heart rate was lower during short-term hypoxia in subjects who developed AMS than in subjects doing well. But significant reverse correlation existed only between AMS scores and heart rate at 7th min after hypoxic breathing (r = -0.176). CONCLUSION: Limited information can be gained on AMS score by assessing physiological responses to short-term hypoxia and breath holding at sea level.