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World J Gastroenterol. Apr 7, 2006; 12(13): 2120-2124
Published online Apr 7, 2006. doi: 10.3748/wjg.v12.i13.2120
Effects of hypobaric hypoxia on adenine nucleotide pools, adenine nucleotide transporter activity and protein expression in rat liver
Cong-Yang Li, Jun-Ze Liu, Li-Ping Wu, Bing Li, Li-Fen Chen
Cong-Yang Li, Jun-Ze Liu, Bing Li, Li-Fen Chen, Department of Pathophysiology, Institute of High Altitude Military Medicine, Third Military Medical University, Chongqing 400038, China
Li-Ping Wu, Xijing Hospital, the Fourth Military Medical University, Xi’an 710032, Shaanxi Province, China
Author contributions: All authors contributed equally to the work.
Supported by the Natural Science Foundation of China, No.30270509
Correspondence to: Professor Jun-Ze Liu, Department of Pathophysiology, Institute of High Altitude Military Medicine, Third Military Medical University, Chongqing 400038, China. liuliu@mail.tmmu.com.cn
Telephone: +86-23-68752336
Received: October 18, 2005
Revised: November 11, 2005
Accepted: November 18, 2005
Published online: April 7, 2006
Abstract

AIM: To explore the effect of hypobaric hypoxia on mitochondrial energy metabolism in rat liver.

METHODS: Adult male Wistar rats were exposed to a hypobaric chamber simulating 5000 m high altitude for 23 h every day for 0 (H0), 1 (H1), 5 (H5), 15 (H15) and 30 d (H30) respectively. Rats were sacrificed by decapitation and liver was removed. Liver mitochondria were isolated by differential centrifugation program. The size of adenine nucleotide pool (ATP, ADP, and AMP) in tissue and mitochondria was separated and measured by high performance liquid chromatography (HPLC). The adenine nucleotide transporter (ANT) activity was determined by isotopic technique. The ANT total protein level was determined by Western blot.

RESULTS: Compared with H0 group, intra-mitochondrial ATP content decreased in all hypoxia groups. However, the H5 group reached the lowest point (70.6%) (P < 0.01) when compared to the control group. Intra-mitochondrial ADP and AMP level showed similar change in all hypoxia groups and were significantly lower than that in H0 group. In addition, extra-mitochondrial ATP and ADP content decreased significantly in all hypoxia groups. Furthermore, extra-mitochondrial AMP in groups H5, H15 and H30 was significantly lower than that in H0 group, whereas H1 group had no marked change compared to the control situation. The activity of ANT in hypoxia groups decreased significantly, which was the lowest in H5 group (55.7%) (P < 0.01) when compared to H0 group. ANT activity in H30 group was higher than in H15 group, but still lower than that in H0 group. ANT protein level in H5, H15, H30 groups, compared with H0 group decreased significantly, which in H5 group was the lowest, being 27.1% of that in H0 group (P < 0.01). ANT protein level in H30 group was higher than in H15 group, but still lower than in H0 group.

CONCLUSION: Hypobaric hypoxia decreases the mitochondrial ATP content in rat liver, while mitochondrial ATP level recovers during long-term hypoxia exposure. The lower level of extra-mitochondrial ATP may be related to the decrease of ANT activity during hypoxia exposure.

Keywords: Adenine nucleotide pool; Hypoxia; Liver; Mitochondria