Document Detail


An X-Ray diffraction study on mouse cardiac cross-bridge function in vivo: effects of adrenergic {beta}-stimulation.
MedLine Citation:
PMID:  16339874     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
To investigate how beta-stimulation affects the contractility of cardiac muscle, x-ray diffraction from cardiac muscle in the left ventricular free wall of a mouse heart was recorded in vivo. To our knowledge, this is the first x-ray diffraction study on a heart in a living body. After the R wave in electrocardiograms, the ratio of the intensities of the equatorial (1,0) and (1,1) reflections decreased for approximately 50 ms from a diastolic value of 2.1 to a minimum of 0.8, and then recovered. The spacing of the (1,0) lattice planes increased for approximately 90 ms from a diastolic value of 37.2 nm to a maximum of 39.1 nm, and then returned to the diastolic level, corresponding to approximately 10% stretch of sarcomere. Stimulation of beta-adrenergic receptor by dobutamine (20 microg/kg/min) accelerated both the decrease in the intensity ratio, which reached a smaller systolic value, and the increase in the lattice spacing. However, the intensity ratio and spacing at the end-diastole were unchanged. The recovery of the lattice spacing during relaxation was also accelerated. The mass transfer to the thin filaments at systole in a beta-stimulated heart was close to the peak value in twitch of frog skeletal muscle at 4 degrees C, showing that the majority of cross-bridges have been recruited with few in reserve.
Authors:
Ryuji Toh; Masakazu Shinohara; Tomofumi Takaya; Tomoya Yamashita; Shigeru Masuda; Seinosuke Kawashima; Mitsuhiro Yokoyama; Naoto Yagi
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2005-12-09
Journal Detail:
Title:  Biophysical journal     Volume:  90     ISSN:  0006-3495     ISO Abbreviation:  Biophys. J.     Publication Date:  2006 Mar 
Date Detail:
Created Date:  2006-02-15     Completed Date:  2006-05-03     Revised Date:  2013-06-07    
Medline Journal Info:
Nlm Unique ID:  0370626     Medline TA:  Biophys J     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1723-8     Citation Subset:  IM    
Affiliation:
Division of Cardiovascular and Respiratory Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan.
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MeSH Terms
Descriptor/Qualifier:
Actins / physiology*,  ultrastructure*
Adrenergic beta-Agonists / administration & dosage
Animals
Dobutamine / administration & dosage*
Heart / drug effects,  physiology*
Male
Mice
Mice, Inbred C57BL
Myocardial Contraction / drug effects,  physiology*
Myosins / physiology*,  ultrastructure*
Protein Conformation / drug effects
X-Ray Diffraction / methods
Chemical
Reg. No./Substance:
0/Actins; 0/Adrenergic beta-Agonists; 34368-04-2/Dobutamine; EC 3.6.4.1/Myosins
Comments/Corrections

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