Effects of short- and long-term hypobaric hypoxia on Bcl2 family in rat heart.
BACKGROUND
Controversial effects of intermittent hypobaric hypoxia such as cardiac damage or cardiac protection are still mysterious. It is unclear if short-term and long-term intermittent hypobaric hypoxic challenges exert different effects on cytochrome c oxidase and Bcl-2 family in rat heart.


METHODS
Sixty Sprague-Dawley rats were randomized assigned into two groups: first, short-term intermittent hypobaric hypoxia (STIHH)-normobaric normoxia (n=10), hypobaric hypoxia (380 mmHg, 12% O2, 8 hr/day) for 1 day (n=10), and for 4 days (n=10) and second, long-term intermittent hypobaric hypoxia (LTIHH)-normobaric normoxia (n=10), hypobaric hypoxia for 1 week (n=10) and 2 weeks (n=10). After STIHH or LTIHH challenge, myocardial morphology, cytochrome c oxidase and pro-apoptotic Bcl-2 family in the excised left ventricle were determined by histological analysis, Western blotting, and RT-PCR.


RESULTS
Increased wall thickness and abnormal myocardial architecture were observed after LTIHH. Cytochrome c oxidase and anti-apoptotic Bcl-2 protein were significantly increased after STIHH, but were decreased after LTIHH. Pro-apoptotic BNIP3 and Bad proteins were significantly decreased after STIHH but increased after LTIHH.


CONCLUSIONS
STIHH appeared to exert protective effects on hearts whereas LTIHH appeared to exert deleterious effects, which imply that deleterious or advantageous effect of cardiac adaptation after intermittent hypobaric hypoxia is tightly time-course dependent.
Lee
Shin-Da
SD
School of Physical Therapy, Chung-Shan Medical University, Taichung, Taiwan, ROC.
Kuo
Wei-Wen
WW
Wu
Chieh-Hsi
CH
Lin
Yueh-Min
YM
Lin
James A
JA
Lu
Min-Chi
MC
Yang
Ai-Lun
AL
Liu
Jer-Yuh
JY
Wang
Shyi-Gang P
SG
Liu
Chung-Jung
CJ
Chen
Li-Mien
LM
Huang
Chih-Yang
CY
D000818:Animals; D003576:Electron Transport Complex IV / Q000378:metabolism*; D015870:Gene Expression; D006321:Heart / Q000502:physiology; D006352:Heart Ventricles / Q000378:metabolism; D000860:Hypoxia / Q000150:complications / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D024101:Mitochondrial Proteins; D023421:Models, Animal; D009206:Myocardium / Q000473:pathology; D009929:Organ Size; D011312:Pressure / Q000009:adverse effects; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D051025:bcl-Associated Death Protein / Q000378:metabolism
C505650:BNIP3 protein, rat; C494821:Bad protein, rat; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051025:bcl-Associated Death Protein; D003576:Electron Transport Complex IV