Hypoxia reoxygenation induces premature senescence in neonatal SD rat cardiomyocytes  

作　　者：Feng-xiang ZHANG Ming-long CHEN Qi-jun SHAN Jian-gang ZOU Chun CHEN Bing YANG Dong-jie XU Yu JIN Ke-jiang CAO 

机构地区：[1]Department of Cardiology, First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China

出　　处：《Acta Pharmacologica Sinica》2007年第1期44-51,共8页中国药理学报（英文版）

基　　金：Project supported by National Natural Science Foundation of China(No 30671073).

摘　　要：Aim： To investigate whether hypoxia reoxygenation induces premature senescence in neonatal Sprague-Dawley （SD） rat cardiomyocytes. Methods： Cardiomyocytes were isolated from neonatal SD rat heart and identified by immunohistochemistry. The control cultures were incubated at 37℃ in a humidified atmosphere of 5% CO2 and 95% air. The hypoxic cultures were incubated in a modular incubator chamber filled with 1% 02, 5% CO2, and balance N2 for 6 h. The reoxygenated cultures were subjected to 1% O2 and 5% CO2 for 6 h, then 21% oxygen for 4, 8, 12, 24, and 48 h, respectively. Cell proliferation was determined using bromodeoxyuridine labeling. The ultrastructure of cardiomyocytes was observed by using an electron microscope. β-Galactosidase activity was determined by using a senescence β-galactosidase Staining Kit. p16^INK4a and telomerase reverse transcriptase （TERT） mRNA levels were measured by real time quantitative PCR. TERT protein expression was determined by immunohistochemistry. Telomerase activities were assayed by using the Telo TAGGG Telomerase PCR ELISA^plus kit. Results： The initial cultures consisted of pure cardiomyocytes identified by immunohistochemistry. The proportion of BrdU positive ceils was reduced significantly in the hypoxia reoxygenation-treated group （P〈0.01）. Under the condition of hypoxia reoxygenation, mitochondrial dehydration appeared; p 16^INK4a and TERT mRNA levels, β-galactosidase activity, TERT protein expression and telomerase activities were all significantly increased （P〈0.01 or P〈0.05）. Conclusion： These data indicate that premature senescence could be induced in neonatal SD rat cardiomyocytes exposed to hypoxia reoxygenation. Although TERT significantly increased, it could not block senescence.Aim： To investigate whether hypoxia reoxygenation induces premature senescence in neonatal Sprague-Dawley （SD） rat cardiomyocytes. Methods： Cardiomyocytes were isolated from neonatal SD rat heart and identified by immunohistochemistry. The control cultures were incubated at 37℃ in a humidified atmosphere of 5% CO2 and 95% air. The hypoxic cultures were incubated in a modular incubator chamber filled with 1% 02, 5% CO2, and balance N2 for 6 h. The reoxygenated cultures were subjected to 1% O2 and 5% CO2 for 6 h, then 21% oxygen for 4, 8, 12, 24, and 48 h, respectively. Cell proliferation was determined using bromodeoxyuridine labeling. The ultrastructure of cardiomyocytes was observed by using an electron microscope. β-Galactosidase activity was determined by using a senescence β-galactosidase Staining Kit. p16^INK4a and telomerase reverse transcriptase （TERT） mRNA levels were measured by real time quantitative PCR. TERT protein expression was determined by immunohistochemistry. Telomerase activities were assayed by using the Telo TAGGG Telomerase PCR ELISA^plus kit. Results： The initial cultures consisted of pure cardiomyocytes identified by immunohistochemistry. The proportion of BrdU positive ceils was reduced significantly in the hypoxia reoxygenation-treated group （P〈0.01）. Under the condition of hypoxia reoxygenation, mitochondrial dehydration appeared; p 16^INK4a and TERT mRNA levels, β-galactosidase activity, TERT protein expression and telomerase activities were all significantly increased （P〈0.01 or P〈0.05）. Conclusion： These data indicate that premature senescence could be induced in neonatal SD rat cardiomyocytes exposed to hypoxia reoxygenation. Although TERT significantly increased, it could not block senescence.

关 键 词：CARDIOMYOCYTES hypoxia reoxygenation p16^(INK4a) telomerase reversetranscriptase BETA-GALACTOSIDASE 

分 类 号：R542.2[医药卫生—心血管疾病]