Document Detail

Interactive effects of K+, acid, norepinephrine, and ischemia on the heart: implications for exercise.
MedLine Citation:
PMID:  9104837     Owner:  NLM     Status:  MEDLINE    
We tested the hypothesis that cardiac ischemia uncouples the beneficial interaction among hyperkalemia, acidosis, and raised plasma catecholamines when these chemicals are changed to mimic their exercise levels. Potassium chloride, lactic acid, and norepinephrine (NE) were infused intravenously for 2 min into anesthetized, artificially ventilated, thoracotomized rabbits during either occlusion of the left circumflex artery (3 min; n = 10) or after a period of prolonged ischemia (20 min; n = 7) that led to a small infarction. NE (1 microg x kg(-1) x min(-1) iv) offset the negative cardiac effects of hyperkalemia (up to 8.7 +/- 0.7 mM) and acidosis (arterial pH 7.09 +/- 0.03) in normal hearts. Cardiac performance was not significantly depressed by either acute or chronic ischemia before any infusions. However, the protective effect of NE during acute ischemia or after prolonged ischemia with hyperkalemia and acidosis was substantially reduced. These results show that cardiac ischemia attenuates the protective action of NE and increases the depressive effects of hyperkalemia and acidosis. Whether myocardial ischemia amplifies the cardiotoxic effects of hyperkalemia and acidosis during vigorous exercise by attenuating the beneficial effect of catecholamines remains to be determined.
M O'Neill; C E Sears; D J Paterson
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  82     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1997 Apr 
Date Detail:
Created Date:  1997-06-26     Completed Date:  1997-06-26     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1046-52     Citation Subset:  IM    
University Laboratory of Physiology, Oxford, United Kingdom.
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MeSH Terms
Acidosis / physiopathology*
Adrenergic alpha-Agonists / pharmacology*
Blood Pressure / drug effects
Heart / drug effects,  physiology*
Hydrogen-Ion Concentration
Hyperkalemia / physiopathology
Myocardial Ischemia / physiopathology*
Norepinephrine / pharmacology*
Physical Conditioning, Animal / physiology*
Physical Exertion / physiology*
Potassium / pharmacology*
Ventricular Function, Left / drug effects,  physiology
Grant Support
//Wellcome Trust
Reg. No./Substance:
0/Adrenergic alpha-Agonists; 51-41-2/Norepinephrine; 7440-09-7/Potassium

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