title: A randomly-controlled study on the cardiac function at the early stage of return to the plains after short-term exposure to high altitude.
abstract: High altitude acclimatization and adaptation mechanisms have been well clarified, however, high altitude de-adaptation mechanism remains unclear. In this study, we conducted a controlled study on cardiac functions in 96 healthy young male who rapidly entered the high altitude (3700 m) and returned to the plains (1500 m) after 50 days. Ninety eight healthy male who remained at low altitude were recruited as control group. The mean pulmonary arterial pressure (mPAP), left ventricular ejection fraction (LVEF), left ventricular fraction shortening (LVFS), cardiac function index (Tei index) were tested. Levels of serum creatine kinase isoform MB (CK-MB), lactate dehydrogenase isoenzyme-1 (LDH-1), endothelin-1 (ET-1), nitrogen oxide (NO), serum hypoxia-inducible factor-1α (HIF-1α), 8-iso-prostaglandin F(2α) (8-iso PGF(2α)), superoxide dismutase (SOD) and malonaldehyde (MDA) were measured at an altitude of 3700 m and 1500 m respectively. The results showed that after short-term exposure to high altitude mPAP and Tei index increased significantly, while LVEF and LVFS decreased significantly. These changes were positively correlated with altitude. On the 15(th) day after the subjects returned to low altitude, mPAP, LVEF and LVFS levels returned to the same level as those of the control subjects, but the Tei index in the returned subjects was still significantly higher than that in the control subjects (P<0.01). We also found that changes in Tei index was positively correlated with mPAP, ET-1, HIF-1α and 8-iso PGF(2α) levels, and negatively correlated with the level of NO, LVEF, LVFS, CK-MB and LDH-1. These findings suggest that cardiac function de-adapts when returning to the plains after short-term exposure to high altitude and the function recovery takes a relatively long time.
authors.affiliation: Department of High Altitude Diseases, College of High Altitude Military Medicine, Third Military Medical University, Chongqing, China. zhouqq9918@yahoo.com.cn
authors.forename: Qiquan
authors.initials: Q
authors.lastname: Zhou
authors.forename: Shengyue
authors.initials: S
authors.lastname: Yang
authors.forename: Yongjun
authors.initials: Y
authors.lastname: Luo
authors.forename: Yushu
authors.initials: Y
authors.lastname: Qi
authors.forename: Ziqiang
authors.initials: Z
authors.lastname: Yan
authors.forename: Zifu
authors.initials: Z
authors.lastname: Shi
authors.forename: Yong
authors.initials: Y
authors.lastname: Fan
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D000531:Altitude; D001794:Blood Pressure / Q000502:physiology; D003402:Creatine Kinase / Q000097:blood; D016207:Cytokines / Q000097:blood; D003971:Diastole / Q000502:physiology; D015237:Dinoprost / Q000031:analogs & derivatives / Q000097:blood; D004781:Environmental Exposure; D005609:Free Radicals / Q000097:blood; D005843:Geography; D006334:Heart Function Tests; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000097:blood; D008297:Male; D008315:Malondialdehyde / Q000378:metabolism; D009206:Myocardium / Q000201:enzymology; D011651:Pulmonary Artery / Q000502:physiology; D013599:Systole / Q000502:physiology; D013997:Time Factors; D055815:Young Adult
chemical_list: D016207:Cytokines; D005609:Free Radicals; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; C075750:8-epi-prostaglandin F2alpha; D008315:Malondialdehyde; D015237:Dinoprost; D003402:Creatine Kinase