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The mechanism of increased postnatal heart rate and sinoatrial node pacemaker activity in mice.
MedLine Citation:
PMID:  23288563     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Heart rate (HR) of mammalian species changes postnatally, i.e., HR of large animals including humans decreases, while HR in small animals such as mice and rats increases. To clarify cellular mechanisms underlying the postnatal HR changes, we performed in vivo HR measurement and electrophysiological analysis on sinoatrial node (SAN) cells in mice. The in vivo HR was ~320 beats min(-1) (bpm) immediately after birth, and increased with age to ~690 bpm at postnatal day 14. Under blockage of autonomic nervous systems, HR remained constant until postnatal day 5 and then increased day by day. The spontaneous beating rate of SAN preparation showed a similar postnatal change. The density of the L-type Ca(2+) current (LCC) was smaller in neonatal SAN cells than in adult cells, accompanied by a positive shift of voltage-dependent activation. Thus, the postnatal increase in HR is caused by both the increased sympathetic influence and the intrinsic activity of SAN cells. The different conductance and kinetics of LCC may be involved in the postnatal increase in pacemaker activity.
Authors:
Takeshi Adachi; Shigehiro Shibata; Yosuke Okamoto; Shinichi Sato; Susumu Fujisawa; Takayoshi Ohba; Kyoichi Ono
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2013-1-4
Journal Detail:
Title:  The journal of physiological sciences : JPS     Volume:  -     ISSN:  1880-6562     ISO Abbreviation:  J Physiol Sci     Publication Date:  2013 Jan 
Date Detail:
Created Date:  2013-1-4     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101262417     Medline TA:  J Physiol Sci     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
Department of Cell Physiology, Akita University Graduate School of Medicine, 1-1-1 Hondo, Akita, 010-8543, Japan.
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