Elucidating the combined effect of intermittent hypoxia training and acetazolamide on hypoxia induced hematological and physiological changes.

As the number of people travelling to altitude increases, the risk of life threatening medical emergencies also increases. It is important that we have effective strategies to minimize the risk of altitude illness. In this study, an attempt was made to investigate the combined effect of non-pharmacological (Intermittent hypoxia training; IHT) and pharmacological (acetazolamide; ACZ) intervention as a prophylactic strategy in order to minimize the risk of high altitude hypoxic related problems using rats as an animal model. Male Sprague Dawley rats were subjected to IHT for 4 h consecutively for 5 days at 12% FiO2 under normobaric conditions with and without oral ACZ administration at 25 mg/kg body weight. Validation of the intervention was performed by exposing the rats to extreme hypoxia (EH) at 8% FiO2 to further assess the effect of IHT and ACZ on hypoxic acclimatization. The principal findings of this study is that the combined effect of IHT and ACZ improves the arterial oxygenation by alterations in hemodynamics and in blood gasometry, thereby resulting into an increase in the oxygen carrying capacity of the blood with increase in SpO2 (peripheral oxygen saturation). The present study showed that the combined effect of IHT with ACZ could be refined as a prophylactic measure for better outcomes during altitude ascent and rapid altitude acclimatization rather than IHT or ACZ alone.

Physiological and oxidative stress responses to intermittent hypoxia training in Sprague Dawley rats.

AIM: Rapid ascent to high altitude and inability to acclimatize lead to high-altitude illnesses. Intermittent hypoxia (IH) conditioning has been hypothesized as a non-pharmacological strategy aiming to improve adaptive responses during high altitude ascent. In the recent years, IH training (IHT) has become increasingly popular among recreational and professional athletes owing to its ability to mitigate high altitude related problems. This study aimed at exploring the role of IHT in altitude acclimatization. METHODS: Male Sprague Dawley rats were subjected to IHT for 4 h consecutively for 5 days at 12% FiO2 under normobaric conditions. To assess the effect of IHT in hypoxic acclimatization, animals were further exposed to extreme hypoxia (EH) at 8% FiO2. Oxygen saturation (SpO2), respiratory rate and heart rate were recorded during the exposure. Oxidative stress (ROS, MDA, and 4-HNE) and histopathological examinations were studied in the lung tissue sections. Hypoxia biomarkers, HIF-1α, EPO, VEGF, and BPGM were evaluated through western blotting in the lung tissue. RESULTS: Assessment of the IHT showed that SpO2 levels were found to be higher in the IH trained rats with a statistical difference of p < 0.01 in the first hour of hypoxia exposure as compared to the untrained rats. There was a significantly higher (p < 0.001) generation of ROS and MDA in the untrained rats as compared to the trained rats. Lipid peroxidation markers and systemic inflammatory marker were found to be expressed at much higher level in the untrained rats. There was a higher expression of HIF-1α (1.24-fold ↑), VEGF (1.14-fold ↑) and decrease in EPO (1.43-fold ↓) in the untrained rats as compared to trained rats. CONCLUSIONS: Preconditioning with IHT resulted in the reduction in hypoxia induced oxidative stress during extreme hypoxia exposure and thus, maintaining redox balance as well as adjustment in the physiological changes in rats.

Reverse translating SULT1A1, a potential biomarker in roentgenographically tested rat model of rapid HAPE induction.

AIMS: HAPE remains the most common lethal high-altitude disease. Although its pathophysiology and other associated causal factors have been partially uncovered along with some potential biomarker proteins, it has not been completely elucidated. A major hindrance to improving the understanding of HAPE pathophysiology and associated molecular events has been the absence of a quick, reliable and definitive animal model of HAPE. This study is aimed at development of a rapid and reliable SD rat model of high altitude pulmonary edema (HAPE) that can be roentgenographically confirmed and be used to study protein markers of HAPE. MAIN METHODS: In this study, we detail the process of rapidly inducing HAPE in male SD rats within 18 h of simulated high-altitude exposure without causing high rates of mortality. Thereafter, we confirmed HAPE using roentgenography. We assessed Sulfotransferase 1A1 (SULT1A1), IL-1 beta, TNF- alpha and IFN-gamma using ELISA. Finally, H&E staining of lung tissues was also performed. KEY FINDINGS: A roentgenographically confirmed HAPE model was demonstrated. SULT 1A1 levels are found to be highest in rats suffering HAPE, as previously confirmed in human patients. Inflammation was also assessed based on levels of inflammatory proteins like IL-1b, TNF-a, and IFN-g in addition to H&E staining of lung tissues. Inflammation and HAPE were observed to be synergistic events and not cause and effect of each other. SIGNIFICANCE: This rat model of HAPE will help researchers and clinicians in evaluating performance of therapies, potential biomarker and also further elucidate underlying molecular processes causing HAPE.

Quercetin as a prophylactic measure against high altitude cerebral edema.

The present study was undertaken to elucidate the intervention of quercetin against high altitude cerebral edema (HACE) using male Sprague Dawley rats as an animal model. This study was also programmed to compare and correlate the effect of both quercetin (flavonoid) and dexamethasone (steroid) against HACE. Six groups of animals were designed for this experiment, (I) normoxia, (II) hypoxia (25,000 ft, 24 h), (III) normoxia+quercetin (50 mg/kg body wt), (IV) normoxia+dexamethasone (4 mg/kg body wt), (V) hypoxia+quercetin (50 mg/kg body wt), (VI) hypoxia+dexamethasone (4 mg/kg body wt). Quercetin at 50 mg/kg body wt, orally 1h prior to hypoxia exposure, was considered as the optimum dose, due to a significant reduction in the level of brain water content and cerebral transvascular leakage (P < 0.001), as compared to control (24 h hypoxia). Dexamethasone was administered at 4 mg/kg body wt, orally, 1h prior to hypoxia exposure. Both drugs (quercetin and dexamethasone) could efficiently reduce the hypoxia-induced hematological changes. Quercetin was observed to be a more potent antioxidative and anti-inflammatory agent. It blocks nuclear factor kappa-beta (NFκB) more significantly (P < 0.05) than the dexamethasone-administered hypoxia-exposed rats. Histopathological findings demonstrate the absence of an edema and inflammation in the brain sections of quercetin-administered hypoxia-exposed rats. The present study reveals quercetin to be a potent drug against HACE, as it efficiently attenuates inflammation as well as cerebral edema formation without any side effects of steroid therapy (dexamethasone).

Purification, characterization and expression kinetics of heat shock protein 70 from Bubalus bubalis.

The present work on Bubalus bubalis (buffalo) was designed to study heat shock protein 70 (HSP70) induction in lymphocytes, its purification and characterization. HSP70 induction and expression kinetics at different temperatures and time durations were also studied. HSP70 purification was carried out by immunoaffinity chromatography using adenosine di-phosphate (ADP-agarose column) and the characterization of the purified protein was done using western blotting by mouse monoclonal anti-HSP70. The molecular weight of HSP70 of buffalo lymphocytes was found to be approximately of 68 kDa and was less than that of bovine brain HSP70. The purified HSP70 was assessed using indirect inhibition enzyme-linked immunosorbent assay (ELISA). A good amount of HSP70 (1430 eta g HSP70/100 microl) was recovered after purification, out of the total 2040.40 eta g of HSP70/100 microl of cell supernatant. To assess the impact of temperature and time dependent variability in the induction and expression pattern of HSP70, buffalo lymphocytes were subjected to three different temperature treatments, viz.: (I) 38 degrees C for 48 h and further exposed the same cells at 45 degrees C for 3 h, (II) 42 degrees C for 3 h, and (III) 45 degrees C for 3 h, respectively. The respective cell viability was found to be 68%, 63%, and 51%. The HSP70 levels were 58.30+/-4.37, 42.59+/-9.04 and 21.95+/-6.79 ng/million cells, respectively, at three temperature exposures. The results indicates that higher intensity and duration of temperature exposure cause higher HSP70 induction in buffalo lymphocytes to maintain cellular homeostasis with a threshold of thermal dose for maximum HSP70 expression. However immediate induction of HSP70 in the lymphocytes was dependent on magnitude of thermal exposure (stress level) and time of thermal exposure (stress duration). The present study on HSP70 and its induction will help likely to solve the problems related to the present scenario of thermo-adaptability in buffaloes.