title: [Effects of Shen-Mai injection on sternohyoid contractile properties in chronic intermittent hypoxia rat].
abstract: OBJECTIVE
  To investigate the effect of Shen-Mai injection (SMI) on sternohyoid contractile properties in rats with chronic intermittent hypoxia.
  
  
  METHODS
  Thirty healthy male SD rats were randomly assigned to three equal groups, the control group (A group), the chronic intermittent hypoxia group (B group) and the SMI group(C group). Rats in B group and C group were exposed to alternating periods of hypoxia and normoxia once per minute for 8 h/d for 5 weeks in order to mimic the intermittent hypoxia of obstructive sleep apnea-hypopnea syndrome (OSAHS) in humans. Isometric contractile properties were determined by electrostimulating the strips of isolated sternohyoid muscles at different frequencies (from 10 Hz to 100 Hz) to observe the changes of the sternohyoid contractile properties.
  
  
  RESULTS
  (1) The tension of sternohyoid muscle in A group at different frequencies was (23.2 +/- 5.6), (26.2 +/- 5.0), (35.1 +/- 5.4), (46.0 +/- 8.5), (57.0 +/- 9.9), (69.9 +/- 9.7), (79.2 +/- 9.5), (85.7 +/- 7.6), (87.9 +/- 7.9), and (86.6 +/- 12.4) g/cm(2). The tension of sternohyoid muscle in B group [(19.5 +/- 4.7), (23.8 +/- 4.7), (33.0 +/- 5.1), (45.1 +/- 5.9), (54.2 +/- 7.0), (66.1 +/- 9.1), (74.2 +/- 9.1), (79.7 +/- 9.0), (82.0 +/- 8.4), and (80.7 +/- 11.8) g/cm(2)] was not significantly different from those in A group respectively (all P > 0.05); while the tension of sternohyoid muscle in C group [(30.5 +/- 2.3), (40.0 +/- 5.4), (56.2 +/- 7.6), (72.2 +/- 6.4), (82.0 +/- 5.5), (92.4 +/- 4.6), (98.1 +/- 4.0), (99.2 +/- 7.4), (101.8 +/- 3.9), and (102.2 +/- 4.0) g/cm(2)] was significantly different from those in B group respectively (all P < 0.05). (2) In fatigue test, the tension percentages of sternohyoid muscle in A group at 1, 2, 3, 4, and 5 min were (87.9 +/- 5.7)%, (72.1 +/- 11.5)%, (55.6 +/- 9.6)%, (39.7 +/- 10.7)%, (33.2 +/- 10.2)%. Compared with A group, the tension percentages of sternohyoid muscle in B group at 1, 2, 3, 4, and 5 min [(75.6 +/- 8.5)%, (41.6 +/- 7.3)%, (29.0 +/- 2.7)%, (20.4 +/- 2.9)%, (18.5 +/- 2.5)%, respectively] decreased significantly (all P < 0.05). Compared with B group, the tension percentages of sternohyoid muscle in C group [(87.9 +/- 4.4)%, (67.9 +/- 14.1)%, (48.4 +/- 9.9)%, (38.2 +/- 7.0)%, (33.8 +/- 9.3)%, respectively] increased significantly (all P < 0.05).
  
  
  CONCLUSIONS
  Chronic intermittent hypoxia can increase upper airway muscle fatigue. SMI can significantly increase the contractile properties of upper airway muscle and resist the fatigue of upper airway muscle.
authors.affiliation: Department of Respiratory Medicine, Affiliated Tongji Hospital, Huazhong University of Science and Technology, Wuhan, China.
authors.forename: Shan-shan
authors.initials: SS
authors.lastname: Liu
authors.forename: Hui-guo
authors.initials: HG
authors.lastname: Liu
authors.forename: Sheng-dao
authors.initials: SD
authors.lastname: Xiong
authors.forename: Ru-ji
authors.initials: RJ
authors.lastname: Niu
authors.forename: Yong-jian
authors.initials: YJ
authors.lastname: Xu
authors.forename: Zhen-xiang
authors.initials: ZX
authors.lastname: Zhang
mesh_terms: D000818:Animals; D004365:Drugs, Chinese Herbal / Q000494:pharmacology*; D000860:Hypoxia / Q000188:drug therapy* / Q000503:physiopathology*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D018482:Muscle, Skeletal / Q000187:drug effects*; D008517:Phytotherapy; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D004365:Drugs, Chinese Herbal