Effects of high altitude hypoxia on the expression of ATP-binding cassette transporter in blood-brain barrier
Objective This study aimed to investigate the effects of high-altitude hypoxia on the expression of ATP-binding cassette(ABC)transport proteins in the blood-brain barrier(BBB)and explore the mechanisms influencing their expression.Methods Wistar rats were divided into 1500 m group(Lanzhou field),4010 m group(simulated 4010 m,low-pressure oxygen chamber,hypoxia for 3 days),6000 m group(simulated 6000 m,low-pressure oxygen chamber,hypoxia for 3 days),phenytoin sodium+1500 m group(given 50 mg·kg-1 phenytoin sodium on the basis of the 1500 m group),phenytoin sodium+4010 m group(given 50 mg·kg-1 phenytoin sodium on the basis of the 4010 m group),phenytoin sodium+6000 m group(given 50 mg·kg-1 phenytoin sodium on the basis of the 6000 m group),and hypoxia 1 d group,hypoxia 2 d group,hypoxia 3 d group,hypoxia 4 d group(simulated altitude of 4010 m,low-oxygen chamber,hypoxia for 1,2,3,4 days).Western blot was used to detect the expression of BBB tissue proteins;and liquid chromatography-tandem mass spectrometry was used to measure the concentration of phenytoin sodium in cerebrospinal fluid.Results The relative expression levels of P-glycoprotein(P-gp)in the 1500 m,4010 m,6000 m groups were 1.00±0.04,1.84±0.02,2.10±0.05,respectively;the relative expression levels of multidrug resistance-associated protein-4(MRP4)were 1.00±0.05,2.77±0.08,4.42±0.03,respectively;the concentrations of phenytoin sodium in cerebrospinal fluid were(864.78±348.32),(1 000.22±273.90),and(1 214.17±314.09)ng·mL-1,respectively.The differences in the above indicators between the 1500 m,4010 m,and 6000 m groups were statistically significant(all P<0.05).The relative expression levels of P-gp in the hypoxia 1 d,2 d,3 d,4 d groups were 1.00±0.03,1.85±0.04,3.10±0.02,2.17±0.05,respectively;the relative expression levels of MRP4 were 1.00±0.05,1.79±0.10,1.60±0.08,1.31±0.06,respectively;the differences in the above indicators between the hypoxia 1 d,2 d,3 d,4 d groups were statistically significant(all P<0.05).Conclusion Different high-altitude hypoxic environments have different effects on the expression of ABC transport proteins in the BBB,influencing the drug concentrations of their substrate drugs in the body.