title: [Studying the mechanism of heart rate slowing down after birth by the method of HRV power spectrum analysis].
abstract: OBJECTIVE
  To explore the neurological mechanism of heart rate slowing down after birth and to investigate if the heart itself participates in the process.
  
  
  METHODS
  With the method of HRV power spectrum analysis, the regulatory mechanisms of autonomic nerves over heart rate were studied on different age groups of human beings and rabbits. Similar experiments were carried out on isolated perfused rabbit hearts in order to study if the heart itself were involved in the process of heart rate slowing down as they grew up.
  
  
  RESULTS
  The ratio of parasympathetic tone to sympathetic one is significantly increased as a child or rabbit grows up while the heart rate becomes slower. The spontaneous beating of isolated rabbit heart also slows down as the rabbit becomes older.
  
  
  CONCLUSIONS
  Both of the nerve factor and heart itself are involved in the process of slowing down of heart rate as a child grows up.
authors.affiliation: Department of Physiology, Shanghai Second Medical University, Shanghai 200025, China.
authors.forename: Xi-Jin
authors.initials: XJ
authors.lastname: Wang
authors.forename: Hong-Wei
authors.initials: HW
authors.lastname: Wang
authors.forename: Zhi-Fang
authors.initials: ZF
authors.lastname: Yang
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D001341:Autonomic Nervous System / Q000502:physiology; D001919:Bradycardia / Q000503:physiopathology*; D002648:Child; D004562:Electrocardiography; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D066298:In Vitro Techniques; D007223:Infant; D007231:Infant, Newborn; D011817:Rabbits; D012815:Signal Processing, Computer-Assisted