title: [Effect of melatonin and/or diazepam on circadian rhythm of cultured myocardiocytes in rats].
abstract: OBJECTIVE
  To investigate the effect of melatonin and/or diazepam on the endogenous rhythm in cultured myocardiocytes and in that connexion to inquire into the mechanism of circadian oscillation level.
  
  
  METHODS
  The beating rate of cultured myocardiocytes was dynamically monitored by an inverted phase-contrast microscope coupled to high speed CCD camera and computer system. Under the culturing condition of artificial light L:D = 12:12, the circadian rhythm variation of cultured myocardiocytes beating frequencies was measured, and then the effect exerted by melatonin and/or diazepam on that circadian rhythm was studied.
  
  
  RESULTS
  It was found that under the L:D = 12:12 culturing condition, the cultured myocardiocytes exhibited prominent circadian rhythm. With the use of melatonin and or diazepam, the circadian rhythm of those myocardiocytes changed, not only the amplitude and mesor decreased, but also the acrophase delayed.
  
  
  CONCLUSIONS
  The modulation of circadian rhythm in cellular level is not only related with endogenous control but also affected by external factors.
authors: Biomedical Engineering Department, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu 610041, China.
authors: Beiyi
authors: B
authors: Zhou
authors: Chaomin
authors: C
authors: Wan
authors: Qizhi
authors: Q
authors: Teng
authors: Dachang
authors: D
authors: Tao
authors: Zhengrong
authors: Z
authors: Wang
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D002940:Circadian Rhythm / Q000187:drug effects* / Q000502:physiology; D005260:Female; D008550:Melatonin / Q000494:pharmacology*; D032383:Myocytes, Cardiac / Q000166:cytology*; D011247:Pregnancy; D051381:Rats; D017208:Rats, Wistar
chemical_list: D008550:Melatonin