| Dependence of myocardial hypothermia tolerance on sources of activator calcium. | |
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MedLine Citation:
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PMID: 9367607 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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To determine the relationship between cardiac hypothermia tolerance and the sources of activator calcium, we selectively modified either the sarcolemmal calcium permeability by nifedipine or the sarcoplasmic reticulum function by caffeine in papillary muscles from both the rat, as a cold sensitive model, and the ground squirrel, Citellus dauricus, a deep hibernator. Both force-interval relationship and cooling performance were investigated. At 25 degrees C, the slope of the force-interval curve of the ground squirrel was nearly double that of the rat. At shorter test intervals 0.5 muM nifedipine moved the curve down with little effect at longer intervals, and the curve slope increased. Caffeine (1 mM) decreased the peak force and eliminated its dependence upon test interval. When the temperature was lowered, rat preparations showed a marked increase of resting tension and aftercontraction between 7 and 12 degrees C and became inexcitable. In contrast, they maintained contractility down to a few degrees above 0 degrees C without aftercontraction and increased resting tension in the ground squirrel. In the rat nifedipine shortened the contractions, prevented the increase of resting tension, and minimized aftercontractions, with little improvement of contractility. Caffeine prolonged the contractions, caused a striking increase of resting tension and aftercontractions, and finally disabled the contractility at about 5-10 degrees C, even in the ground squirrel. We conclude that depressed calcium influx helps to prevent hypothermic calcium overload of the cardiac cells. Good function of the sarcoplasmic reticulum is essential for tolerance of hypothermia by cardiac cells. A suggestion that may improve the hypothermic tolerance of the myocardium from nonhibernators is postulated. |
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Authors:
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S Q Wang; Y H Huang; K S Liu; Z Q Zhou |
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Publication Detail:
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Type: Comparative Study; Journal Article |
Journal Detail:
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Title: Cryobiology Volume: 35 ISSN: 0011-2240 ISO Abbreviation: Cryobiology Publication Date: 1997 Nov |
Date Detail:
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Created Date: 1998-01-06 Completed Date: 1998-01-06 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0006252 Medline TA: Cryobiology Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 193-200 Citation Subset: IM; S |
Copyright Information:
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Copyright 1997 Academic Press. |
Affiliation:
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College of Life Sciences, Peking University, Beijing, 100871, People's Republic of China. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adaptation, Physiological Animals Caffeine / pharmacology Calcium / metabolism* Calcium Channel Blockers / pharmacology Female Hibernation / physiology Hypothermia / metabolism*, physiopathology Hypothermia, Induced Male Myocardial Contraction / drug effects Myocardium / metabolism* Nifedipine / pharmacology Rats Sciuridae Species Specificity |
| Chemical | |
Reg. No./Substance:
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0/Calcium Channel Blockers; 21829-25-4/Nifedipine; 58-08-2/Caffeine; 7440-70-2/Calcium |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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