ISSN:
1439-6327
Keywords:
Practolol
;
Atropine
;
Work
;
VO2 max
;
Cardiac frequency
;
Catecholamines
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract The changes in plasma catecholamine concentration (δC) following Β-blockade (practolol, 15 mg) and atropinisation (Atropine, 1.8 mg) have been studied on 5 healthy male subjects during exercise on a motor driven treadmill. The results showed that for a given VO2 and % VO2 max, Β blockade was without effect on δC (except in one athletic subject), but atropine produced a rise in δC. In relation to Q, both drugs produced an increase in δC, but for a given cardiac frequency (f H ) δC was higher with Β blockade, and lower with atropinisation than found in control experiments. The intra- and inter-subject variability of δC in relation to f H was resolved by considering the change in cardiac frequency calculated from baseline value obtained during walking at 6.44 km/h on the level, and expressed as a percentage of the maximal f H attainable for given individuals under the different drug and control conditions (% δf H ). It was concluded that during short term exercise, the rise of δC in relation to % δf H reflects both the myocardial sensitivity to vagal and Β blockade, and the circulatory vasoconstrictor control of blood vessels which is required to sustain increases in systemic and muscle blood flow.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00421633
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