Effects of hypoxia on the expression and function of P-gp in Caco-2 cells / 中南大学学报(医学版)

OBJECTIVES@#Hypoxia can alter the oral bioavailability of drugs, including various substrates (drugs) of P-glycoprotein (P-gp), suggesting that hypoxia may affect the function of P-gp in intestinal epithelial cells. Currently, Caco-2 monolayer model is the classic model for studying the function of intestinal epithelial P-gp. This study combines the Caco-2 monolayer model with hypoxia to investigate the effects of hypoxia on the expression and function of P-gp in Caco-2 cells, which helps to elucidate the mechanism of changes in drug transport on intestinal epithelial cells in high-altitude hypoxia environment.@*METHODS@#Normally cultured Caco-2 cells were cultured in 1% oxygen concentration for 24, 48, and 72 h, respectively. After the extraction of the membrane proteins, the levels of P-gp were measured by Western blotting. The hypoxia time, with the most significant change of P-gp expression, was selected as the subsequent study condition. After culturing Caco-2 cells in transwell cells for 21 days and establishing a Caco-2 monolayer model, they were divided into a normoxic control group and a hypoxic group. The normoxic control group was continuously cultured in normal condition for 72 h, while the hypoxic group was incubated for 72 h in 1% oxygen concentration. The integrity and polarability of Caco-2 cells monolayer were evaluated by transepithelial electrical resistance (TEER), apparent permeability (Papp) of lucifer yellow, the activity of alkaline phosphatase (AKP), and microvilli morphology and tight junction structure under transmission electron microscope. Then, the Papp of rhodamine 123 (Rh123), a kind of P-gp specific substrate, was detected and the efflux rate was calculated. The Caco-2 cell monolayer, culturing at plastic flasks, was incubated for 72 h in 1% oxygen concentration, the expression level of P-gp was detected.@*RESULTS@#P-gp was decreased in Caco-2 cells with 1% oxygen concentration, especially the duration of 72 h (P<0.01). In hypoxic group, the TEER of monolayer was more than 400 Ω·cm2, the Papp of lucifer yellow was less than 5×10-7 cm/s, and the ratio of AKP activity between apical side and basal side was greater than 3. The establishment of Caco-2 monolayer model was successful, and hypoxia treatment did not affect the integrity and polarization state of the model. Compared with the normoxic control group, the efflux rate of Rh123 was significantly reduced in Caco-2 cell monolayer of the hypoxic group (P<0.01). Hypoxia reduced the expression of P-gp in Caco-2 cell monolayer (P<0.01).@*CONCLUSIONS@#Hypoxia inhibits P-gp function in Caco-2 cells, which may be related to the decreased P-gp level.

Progress on factors affecting gastrointestinal function and drug protection in high altitude hypoxia environment / 药学实践杂志

Due to factors such as low pressure, low oxygen and cold in the plateau environment, people who enter the plateau rapidly are susceptible to digestive system diseases, such as upper abdominal pain, loss of appetite, nausea and vomiting and other gastrointestinal dysfunction, which seriously affect the health and work ability of people who enter the plateau rapidly. The gastrointestinal dysfunction caused by the rapid advance to the plateau is mainly reflected in three aspects: gastrointestinal motility dysfunction, impaired mucosal barrier function, and intestinal flora imbalance. At present, the pathogenesis of gastrointestinal dysfunction is still not very clear, and there are fewer drugs for targeted prevention and treatment. Gastrointestinal hormones, oxygen free radicals, inflammatory factors, intestinal flora and other factors, as well as the protective effects of related drugs were reviewed in this paper to provide treatment options and theoretical basis for the prevention and treatment of the gastrointestinal emergency response caused by entering the plateau.

Determination of total polyphenols and catechins in betel nut polyphenol extract / 药学实践杂志

Objective To establish a method for the determination of total polyphenols and catechins in betel nut polyphenols extract, and provide reference for the quality control of betel nut polyphenols extract. Methods The content of total phenol in betel nut extract was determined by ultraviolet spectrophotometry. The content of catechins was determined by HPLC. Results The linear range of total polyphenols in betel nuts extract was 9.8~58.8 μg/ml. The three components of catechin, epicatechin and protocatechuic acid were completely separated by HPLC, and the linear relationship was good in their respective ranges, with the recoveries between 99.17% and 101.67%, the RSD between 1.2% and 2.5%. Conclusion The established method is simple, stable and reliable, which could be used for the quantitative analysis of betel polyphenol extract, and provide experimental basis for the quality control of betel polyphenol extract.

Pharmacodynamic of cilostazol for anti-altitude hypoxia / 中南大学学报(医学版)

OBJECTIVES@#The plateau environment is characterized by low oxygen partial pressure, leading to the reduction of oxygen carrying capacity in alveoli and the reduction of available oxygen in tissues, and thus causing tissue damage. Cilostazol is a phosphodiesterase III inhibitor that has been reported to increase the oxygen release of hemoglobin (Hb) in tissues. This study aims to explore the anti-hypoxic activity of cilostazol and its anti-hypoxic effect.@*METHODS@#A total of 40 male BALB/C mice were randomly divided into a low-dose cilostazol (6.5 mg/kg) group, a medium-dose (13 mg/kg) group, a high-dose (26 mg/kg) group, and a control group. The atmospheric airtight hypoxia experiment was used to investigate the anti-hypoxic activity of cilostazol and to screen the optimal dosage. Twenty-four male Wistar rats were randomly divided into a normoxia control group, a hypoxia model group, an acetazolamide (22.33 mg/kg) group, and a cilostazol (9 mg/kg) group. After 3 days of hypoxia in the 4 010 m high altitude, blood from the abdominal aorta was collected to determine blood gas indicators, the levels of IL-6 and TNF-α in plasma were determined by enzyme-linked immunosorbent assay, and the levels of malondialdehyde (MDA), superoxide dismutase (SOD), and glutataione (GSH) were measured. The degree of pathological damage for rat tissues was observed with HE staining.@*RESULTS@#Compared with the control group, the survival time of mice in the low, medium, and high dose group of cilostazol was significantly prolonged, and the survival time of mice in the medium dose group was the longest, with an extension rate at 29.34%, so the medium dose was the best dose. Compared with the hypoxia model group, the P50 (oxygen partial pressure at Hb oxygen saturation of 50%) value of rats in the cilostazol group was significantly increased by 1.03%; Hb and Hct were significantly reduced by 8.46% and 8.43%, and the levels of IL-6 and TNF-α in plasma were reduced by 50.65% and 30.77%. The MDA contents in heart, brain, lung, liver, and kidney tissues were reduced by 37.12%, 29.55%, 25.00%, 39.34%, and 21.47%, respectively. The SOD activities were increased by 94.93%, 9.14%, 9.42%, 13.29%, and 20.80%, respectively. The GSH contents were increased by 95.24%, 28.62%, 28.57%, 20.80%, and 44.00%, respectively. The results of HE staining showed that compared with the hypoxia model group, cilostazol significantly improved the damage of heart, lung, and kidney tissues in rats after hypoxia.@*CONCLUSIONS@#Cilostazol can significantly improve the oxidative stress and inflammatory reaction caused by rapid altitude hypoxia, and it has a significant protective effect on tissue damage caused by hypoxia, suggesting that it has obvious anti-hypoxic activity.

Anti-hypoxic pharmacological effects of betelnut polyphenols / 中南大学学报(医学版)

Areca catechu L. medicinal materials and their preparations are widely used in clinical practice. Betelnut polyphenol is one of the main chemical components with antioxidant, anti-inflammatory, and antibacterial effects. With continuous increase of high altitude activities, tissue oxidative damage caused by high altitude hypoxia seriously affects the ability to work, and the studies on anti-hypoxia drugs are particularly important. Recent studies have shown that betelnut polyphenols have protective effects on oxidative stress injury caused by hypoxia via improving blood gas index of hypoxic organism, increasing superoxide dismutase glutathione catalase activity, and scavenging excessive free radicals. The effects of betelnut polyphenols against hypoxia and oxidative damage protection suggest that betelnut polyphenols can be used as potential anti-hypoxia drugs and posses clinical prospects.

Research progress of pharmacokinetic factors of metformin / 中国药房

Metformin is the most common first-line oral hypoglycemic drug ，but there are large individual differences in pharmacokinetic parameters and pharmacodynamics during clinical use. The dosage of some patients should be adjusted to achieve satisfactory therapeutic effect. Pharmacokinetic parameters of metformin are affected by many factors ，including respects of transporter gene polymorphism ，drug interaction ，intestinal flora ，plateau hypoxia and physiological function and so on. In order to guide the clinical individualized use of metformin ，this study reviews the research progress on the influencing factors of metformin pharmacokinetics.

Advances in research on the impact of the plateau environmental on the drug metabolism / 药学实践杂志

Plateau environment will affect the metabolism of drugs in the body, which will cause changes in pharmacokinetic parameters, expression and function of drug metabolizing enzymes and transporters. With the rapid development of the pharmaceutical industry, therapeutic drug monitoring (TDM) has been widely paid attention to as a basis for personalized drugs. What impact does the plateau environment on monitoring drugs? In this literature review, we will summarize the types of commonly used therapeutic monitoring drugs, therapeutic windows, and blood samples, analyze the effects of plateau hypoxic environment on the metabolism of commonly used monitoring drugs, provide a reference for the clinical treatment and monitoring drugs of plateau, better ensure the rational use of drugs in the plateau population, and also provide a reference for the later research group to conduct the monitoring of plateau therapeutic drugs and the selection of research drugs.

Effects of acute hypoxia on expression of pregnane X receptor in liver tissues of rats exposed to high altitude / 浙江大学学报·医学版

OBJECTIVE: To investigate the effects of high-altitude hypoxic environment on the expression of pregnane X receptor (PXR) in rat liver and related mechanism. METHODS: Wistar rats were randomly divided into five groups with 8 rats in each group, the rats were exposed to high-plateau hypoxia for 0 (control group), 12, 24, 36 and 48 h, respectively. Abdominal aortic blood samples were collected for blood gas analysis. HE staining was used to observe the pathological changes of liver tissue. The expression levels of PXR mRNA in liver tissues were determined by RT-PCR. Western blot analysis was performed to determine the protein expression of PXR and protease SUG1 in liver tissues of rats. RESULTS Compared with the control group, the blood pH of the rats decreased after 12 h of acute hypoxia. After 24 h exposed to hypoxia, SaO2 was lower than 80%, PaO2 was lower than 60 mmHg (1 mmHg=0.133 kPa); and PaCO2 increased after 48 h exposed to hypoxia (P<0.05). There was obvious edema in the central vein of the liver tissue at 12 h and 24 h after exposure to hypoxia. The liver tissue of the rats exposed to hypoxia for 36 h and 48 h showed inflammatory infiltration. The expression of PXR mRNA was significantly decreased by 63%, 96%, 86%, and 85%at 12, 24, 36 h, and 48 h after exposure to hypoxia (all P<0.05), respectively. The protein expression of PXR was significantly up-regulated by 93%and 99%after 36 h and 48 h exposure to hypoxia (all P<0.05), respectively. The protein expression of proteinase SUG1 decreased by 14%, 34%and 46%after 24, 36 and 48 h after hypoxia (all P<0.01). CONCLUSIONS Acute hypoxia at high altitude can affect the expression of nuclear receptor PXR in rat liver, and protease SUG1 may be a regulatory factor for PXR expression in hypoxia.