Document Detail


Cardiovascular, ventilatory and catecholamine responses to maximal dynamic exercise in partially curarized man.
MedLine Citation:
PMID:  3681737     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
1. In ten young men the ventilatory, cardiovascular, catecholamine and metabolic responses to maximal dynamic leg exercise on a stationary bicycle were followed during partial neuromuscular blockade with tubocurarine. Maximal exercise was performed when the drug effect was at its maximum as well as during the subsequent reduction in the effect allowing a gradually increasing work intensity. The results were compared with those obtained during submaximal and maximal exercise performed without tubocurarine. Partial neuromuscular blockade decreased hand-grip strength to 41 +/- 1.1% (S.E. of mean) and the maximal work load to 27 +/- 2.4% of control values. Voluntary effort was maximal and the rate of perceived exertion was high at all levels of exercise with tubocurarine indicating a maintained intense central nervous motor command. 2. During maximal action of the drug oxygen uptake was 1.67 +/- 0.11 l/min while only 0.91 +/- 0.13 l/min (P less than 0.01) at the same work intensity without neuromuscular blockade. This difference may reflect a dominant reliance on fast-twitch muscle fibres when work was performed under the influence of tubocurarine. 3. Compared at a given oxygen uptake ventilation was higher during work with tubocurarine than during control exercise (e.g. 55 +/- 4.2 and 40 +/- 2.2 l/min, respectively (P less than 0.01), at a mean oxygen uptake of 1.9 l/min), while heart rate did not differ significantly (146 +/- 4.4 and 139 +/- 3.0 beats/min). With decreasing drug effect both variables increased towards the maximum values of 138 +/- 4.5 l/min and 183 +/- 3.9 beats/min, respectively, achieved in control experiments at an oxygen uptake of 3.8 +/- 0.2 l/min. Like heart rate the mean arterial blood pressure increased with increasing work load and was similar at a given oxygen uptake with and without tubocurarine. 4. During maximal exercise at peak tubocurarine effect plasma adrenaline and noradrenaline concentrations were smaller than during control maximum, 1.6 +/- 0.27 versus 3.4 +/- 0.55 nmol/l (P less than 0.01) and 7.5 +/- 1.3 versus 12.6 +/- 1.8 nmol/l (P less than 0.05), respectively. However, comparisons at identical oxygen uptake rates revealed that catecholamine responses were markedly enhanced during tubocurarine treatment. Also, blood lactate concentrations were smaller at peak tubocurarine action than during control maximum, 1.9 +/- 0.42 mmol/l and 6.1 +/- 0.49 mmol/l (P less than 0.01).(ABSTRACT TRUNCATED AT 400 WORDS)
Authors:
H Galbo; M Kjaer; N H Secher
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of physiology     Volume:  389     ISSN:  0022-3751     ISO Abbreviation:  J. Physiol. (Lond.)     Publication Date:  1987 Aug 
Date Detail:
Created Date:  1988-01-11     Completed Date:  1988-01-11     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  0266262     Medline TA:  J Physiol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  557-68     Citation Subset:  IM; S    
Affiliation:
Department of Medical Physiology B, Panum Institute, University of Copenhagen, Denmark.
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MeSH Terms
Descriptor/Qualifier:
Adult
Epinephrine / blood
Hemodynamics / drug effects*
Humans
Male
Neuromuscular Junction / drug effects*
Norepinephrine / blood
Physical Exertion / drug effects*
Respiration / drug effects*
Tubocurarine / pharmacology*
Chemical
Reg. No./Substance:
51-41-2/Norepinephrine; 51-43-4/Epinephrine; 57-95-4/Tubocurarine
Comments/Corrections

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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