Heat acclimation provides cardiovascular protection in high-temperature environments through multilevel mechanisms; however, the complete molecular basis of its effects remains unclear. In this paper, we systematically review the effects of heat acclimation on blood volume, vascular function, cardiac structure, energy metabolism, and anti-stress regulation, revealing their potential mechanisms in cardiovascular adaptive protection. We also summarizes the multilevel responses induced by heat stress and heat acclimation, including the modulatory effects of heat acclimation on heat shock proteins (HSPs), hypoxia inducible factor 1 (HIF-1), and apoptotic pathways. Additionally, we highlights the comprehensive protective effects of heat acclimation across various stressors (e.g., hypoxia, heat stress). This review provides a significant physiological basis for cardiovascular disease management and sports medicine, emphasizing the potential application of heat acclimation in response to multiple stressors and supporting its role as an effective tool in cardiovascular health management and stress protection interventions.
Humans ; Acclimatization/physiology* ; Hot Temperature ; Heat-Shock Proteins/metabolism* ; Animals ; Heat-Shock Response/physiology* ; Hypoxia-Inducible Factor 1/metabolism* ; Apoptosis/physiology*

OBJECTIVETo investigate the difference of liver enzyme levels and its correlation with serum ACE/ACE2 among yak and cattle on Qinghai-Tibetan plateau, and to further explore the biochemical mechanism of their liver of altitude adaptation.

METHODSThe serum samples of yak were collected at 3,000 m, 3,500 m, 4,000 m and 4,300 m respectively, meanwhile the serum samples of migrated cattle on plateau (2,500 m) and lowland cattle (1,300 m) were also collected. The levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), cholinesterase (CHE), gamma glutamyl transferase (GGT), alkaline phosphatase (ALP), serum lipase (LPS), angiotensin converting enzyme(ACE), angiotensin converting enzyme-2 (ACE2) in serum were measured by using fully automatic blood biochemcal analyzer. We analysed the differences of the above enzymes and its correlation with ACE/ACE2. We used one way analysis of variance (ANOVA).

RESULTSThe levels of ALT in 4,000 m group and 4,300 m group of yak increased significantly compared with other groups, there were no statistically significant differences in AST, CHE, GGT, ACE/ACE2 levels of yaks at different altitudes. As compared to lowland cattle, the serum levels of AST and CHE were increased, the level of LPS and ACE was decreased significantly, respectively, and especially, the ratio of ACE/ACE2 of migranted cattle reduced nearly two times. The levels of LPS were significantly correlated to the ratio of ACE/ACE2 in yak (r = 0.357, P < 0.01), and a high correlation between ALP and ACE/ACE2 in lowland cattle( r = 0.418, P < 0.05), But the biggest contribution rate of the ratio of ACE/ACE2 was only 17.5% for the changes of the levels of liver enzyme.

CONCLUSIONThe results indicated that with the altitude increased did not significantly influence the changes of liver enzymes' activities in mountainous yaks but not in cattle. However, all above these changes weren't actually correlated to the ratio of ACE/ACE2.

Acclimatization ; Alanine Transaminase ; blood ; Alkaline Phosphatase ; blood ; Altitude ; Animals ; Aspartate Aminotransferases ; blood ; Cattle ; physiology ; Cholinesterases ; blood ; Hypoxia ; blood ; Lipase ; blood ; Liver ; enzymology ; Peptidyl-Dipeptidase A ; blood ; gamma-Glutamyltransferase ; blood

OBJECTIVEIncidence and severity of motion sickness (MS) in hot-humid environment are extremely high. We tried to know the effect of two-stage training for reducing incidence and severity of ms.

METHODSSixty male subjects were divided into experimental group and control group randomly. Subjects in experimental group received: (2) adaptation training including sitting, walking and running in hot lab. After adaptation confirmation based on subjective feeling, rectal temperature, heart rate, blood Pressure, sweat rates and sweat salt concentration, we tested both groups by Coriolis acceleration revolving chair test and recorded Graybiel's score and grading of severity to evaluate whether adaptation training was useful; (2) Anti-dizzy training 3m later of deacclimatization contained revolving chair training for 10 times. Then we did the same test as mentioned above to evaluate effect of anti-dizzy training. RESULST: Graybiel' s score and grading of severity had no difference between two groups through acclimatization training (P > 0.05). While they had difference through anti-dizzy training (P < 0.01).

CONCLUSIONAdaptation training seems useless for reducing incidence and severity of MS in hot-humid environment, but anti-dizzy training is useful.

Acclimatization ; physiology ; Adolescent ; Hot Temperature ; Humans ; Male ; Motion Sickness ; physiopathology ; prevention & control ; Young Adult

OBJECTIVEThis study was aimed to explore the physiological changes and the effect of heat acclimation training via a randomized control trial study.

METHODSForty healthy male volunteers were chosen and divided into experimental group and control group randomly. Those in experimental group received heat acclimation training including but not limited to meditation, unarmed run, yoga, and stepping in hot lab environment. And then, subjective feeling, rectal temperature, average skin temperature, and sweat electrolytes concentration were detected in order to describe their physiological changes. Before and after the training, both groups received some tests and their 3 000 m run-race time, nervous reaction time and subjective perception scores were recorded to evaluate the effect of acclimation training.

RESULTS(1) There was no difference in 3 000 m between the 2 groups in the same environment. Subjects' 3 000 m race time in experimental group was obviously shortened than that in control group in room temperature environment (t = 2.326, P < 0.05). And subjects' 3 000 m race time in experimental group was obviously shortened than that in control group in hot-humid environment (t = 4.518, P < 0.01). (2) Subjects' reaction time (RT) in experimental group was shortened than that in control group in room temperature environment (Z = 11.258, P < 0.05). And Subjects' RT in experimental group was sharply shortened than that in control group in hot-humid environment (Z = 6.519, P < 0.01). (3) No difference between the experimental and control groups was observed in subjective perception score (SPS) in room temperature environment. But subjects' SPS in experimental group was obviously lowered than that in control group and in hot-humid environment (t = 17.958, P < 0.01).(4) Anal temperature (AT) was lowered during training, while the change of mean skin temperature (MST) was not significant. Sweat sodium concentration (SSC) was lowered during training. SPS continued to decrease and entered plateau on the 13th day after training.(5) After acclimation training, the working capacity of the experimental group in hot-humid environment was over 85% of that in room temperature environment. While subjects' working capacity in control group in hot-humid environment was about 80% of that in room temperature environment.

CONCLUSIONHot-humid environment acclimation training improved the working capacity. After training, subjects' working capacity in hot-humid environment remained over 85% of that in room temperature environment, which was higher than that of those subjects who did not take part in training.

Acclimatization ; physiology ; Body Temperature ; Heart Rate ; Hot Temperature ; Humans ; Humidity ; Male ; Physical Conditioning, Human ; physiology ; Sweating

OBJECTIVETo establish an effective and stable rabbit heat acclimatization model for the experiment of heat acclimatization mechanisms.

METHODSSixteen healthy male rabbits were divided into heat acclimatization group and control group randomly (n = 8). Heat acclimatization (HA) group was kept in simulation chamber with dry bulb temperature of (36 +/- 1) degrees C, wet bulb temperature of (29 +/- 0.5) degrees C, black-bulb temperature of (40 +/- 1.0) degrees C, 100 min/day for 21 days. Control group was kept in the room with temperature of 20 degrees C and relative humidity < 60% during 20 days, then removed into simulation chamber on day 21 to estimate and monitor the rectal temperature together with the heat acclimatization group. Venous blood of control and heat acclimatization group before and after heat exposure on the 1st day, 11th day and 21st day were collected to detect levels of tumor necrosis factor-alpha (TNF-alpha), interleukin 6 (IL-6) and heat shock protein 70 (HSP70) by ELISA analysis.

RESULTS(1) Rectal temperature: There was no significant change in control group during 21 days. In heat acclimatization group, it increased (2.07 +/- 0.43) degrees C after the 1st exposure, and increased (1.78 +/- 0.37) degrees C after the 11th exposure, the range of increasing decreased (0.29 +/- 0.09) degrees C. After the 21st exposure, it increased (1.52 +/- 0.29) degrees C, which was (0.55 +/- 0.14) degrees C lower than that of the 1st (P < 0.05),and (0.53 +/- 0.14) degrees C lower to that of the control group under 1st heat stress (P < 0.05); (2) The level of TNF-alpha after the 1st exposure increased significantly (P < 0.05), but didn't raise along with the exposure times. And fell back to the original level after the 11th and 21st exposure. Compared with control group, the level of IL-6 increased after the 1st, 11th and 21st exposure (P < 0.05), and maintained highly after the 11th and 21st exposure. Compared with the control group, the level of HSP70 increased dramatically with the heat exposure times. Significant increasing of (HSP70) could be detected after the 11th and 21st exposure (P < 0.05), but there was no difference to that of the 1st exposure.

CONCLUSIONProlonged or repeated exposure to heat stressful environmental conditions can reduce the physiological strain, improve heat tolerance, elicits heat acclimatization.

Acclimatization ; physiology ; Animals ; Body Temperature Regulation ; physiology ; Disease Models, Animal ; HSP70 Heat-Shock Proteins ; metabolism ; Heat Stress Disorders ; metabolism ; physiopathology ; Hot Temperature ; Male ; Rabbits

AIM: Artemisia amygdalina Decne. (Asteraceae) is a critically endangered and endemic herb of Kashmir Himalayan sub-alpine region and Pakistan. Scientific research throughout the world has evidence to support the tremendous medicinal utility of the genus Artemisia. The natural resources of medicinal plants are being reduced day by day. This study provides the alternative way for medicinal resource utilization and conservation of A. amygdalina. METHODS: In vitro-raised plants and greenhouse acclimatized plants were obtained by culturing wild explants on Murashige and Skoog's medium. Plant extracts were obtained and subjected to different antioxidant assays: DPPH assay, riboflavin photo-oxidation assay, deoxy ribose assay, ferric thiocyanate assay, thiobarbituric acid assay, post mitochondrial supernatant assay and DNA damage on agarose gel. RESULTS: In vitro grown plants, as well as those acclimatized in the greenhouse reveals antioxidant activity against hydroxyl, superoxide, and lipid peroxyl radicals. CONCLUSION This preliminary study revealed the free radical scavenging potential of tissue culture-raised plant extracts of A. amydalina.
Acclimatization ; Artemisia ; chemistry ; growth & development ; physiology ; Free Radical Scavengers ; chemistry ; Plant Extracts ; chemistry ; Tissue Culture Techniques

Acclimatization is a process of biological adaptation when exposed to environmental factors such as hypoxia, cold and heat for prolonged periods of time, where non-genetical variations play a role in allowing subjects to tolerate hypoxic, cold or hot environments. This review focuses on the characteristics and mechanisms of acclimatization found through major research advances by our institute. First, the mechanisms underlying the acclimatization to extreme environments are complex. In our investigations, the physiological changes of multiple systems including the nervous, circulatory, respiratory, and hemopoietic system were demonstrated when the acclimatization to hypoxia was developed, and the underlying significance of hypoxia-inducible factor-1 (HIF-1) was investigated. Second, it is suggested that the development of acclimatization to extreme environments is complicated. Hypoxia and cold coexist at high altitude. Our investigations revealed the characteristics of negative cross-relationship in the acclimatization to hypoxia and cold. And third, it is interesting for us to understand that acclimatization to extreme environments is transferable among individuals, and the characteristics of heat acclimatization-inducing factor (HAlF) were presented. The above findings will provide a theoretical guidance for protective operations and help to establish a solid foundation for future research related to acclimatization.
Acclimatization ; physiology ; Altitude ; Cold Temperature ; Environment ; Hot Temperature ; Humans ; Hypoxia ; Hypoxia-Inducible Factor 1, alpha Subunit ; metabolism

Acclimatization ; physiology ; Adult ; Altitude ; Fatty Acid-Binding Proteins ; metabolism ; Humans ; Male ; Middle Aged ; Myelin Basic Protein ; metabolism ; Nervous System Diseases ; metabolism ; Occupational Exposure ; Succinate Dehydrogenase ; metabolism

OBJECTIVETo observe the changes of erythrocyte deformability in rats acclimatized to hypoxia and its molemechanism.

METHODSMale rats were randomly divided into three groups (n = 10): normal control group, acute hypoxia group and hypoxia acclimatization group. Animals were exposed to hypoxia for 0, 1, 28 d, blooded from their hearts after anaesthetized, respectively. Erythrocyte deformability, membrane fluidity, cholesterin and total lipid, lipid components of erythrocyte membrane, erythrocyte membrane ATPase and the concentrations of Na+ and Ca2+ were measured respectively. The two-dimensional electrophoresis maps of the rats erythrocyte membrane protein were achieved. The different protein spots were founded by image master 2D elite and identified by mass spectrum.

RESULTS(1) In acute hypoxia group, the deformability, membrane fluidity, the content of membrane cholesterin and total lipid were declined. The content of phosphatidylserines (PS), sphingomyelin (SM) in erythrocyte membrane lipids were increased, phosphatidylcholine (PC) reduced. The activity of ATP enzymes reduced and the concentration of Na+ and Ca2+ in erythrocyte increased. The two-dimensional electrophoresis maps of the rats erythrocyte membrane protein were achieved. Four of the seven protein spots selected increased and three of them showed no change. (2) In hypoxia acclimatization group, the deformability, membrane fluidity, the content of membrane cholesterin and total lipid were increased than those in acute hypoxia group, similar to normal group. The content of PS, SM in erythrocyte membrane lipids were reduced, PC increased. The activity of ATP enzymes induced and the concentration of Na+ and Ca2+ in erythrocyte increased after hypoxia acclimatization. Four of those protein spots mentioned increase and three declined after hypoxia acclimatization. They were respectively proved by mass spectrum to be alexin binding protein, aquaporin chip, membrane inhibitor reactive lysis, phospholipids scramblase, glucose transferase, aminophospholipid translocases, ATP-dependent floppase, the latter three proteins were associate with the overturning of erythrocyte membrane lipids.

CONCLUSIONAcute hypoxia caused the corresponding damage of erythrocyte deformability, erythrocyte membrane fluidity, erythrocyte membrane proteins erythrocyte expression, the activity of membrane ATPase and the concentration of Na+ and Ca2+ in erythrocyte. The parameters above were improved after hypoxia acclimatization, so hypoxia acclimatization effected positively in the damage to erythrocyte due to acute hypoxia. The three membrane proteins might play important roles in the deformability improved by hypoxia acclimatization, which included phospholipids scramblase, aminophospholipid translocases and ATP-dependent floppase.

Acclimatization ; physiology ; Adenosine Triphosphatases ; metabolism ; Altitude ; Animals ; Calcium ; metabolism ; Erythrocyte Deformability ; physiology ; Erythrocyte Membrane ; metabolism ; Hypoxia ; blood ; physiopathology ; Male ; Membrane Fluidity ; Phospholipid Transfer Proteins ; metabolism ; Rats ; Sodium ; metabolism

Acclimatization ; physiology ; Altitude ; Altitude Sickness ; prevention & control ; Humans ; Hypoxia ; physiopathology ; Male ; Military Personnel ; Mountaineering ; physiology ; Oxygen Consumption ; physiology ; Physical Fitness ; physiology ; Young Adult