Document Detail


Voluntary exercise does not affect stress-induced tachycardia, but improves resistance to cardiac arrhythmias in rats.
MedLine Citation:
PMID:  21039755     Owner:  NLM     Status:  In-Process    
Abstract/OtherAbstract:
1. It is currently unknown whether long-term voluntary exercise has enduring cardioprotective effects in animal models. 2. The present study was conducted in three groups of rats: (i) sedentary controls (n = 6); (ii) 24 h runners (n = 8; unlimited access to running wheels); and (iii) 2 h runners (n = 8; access to running wheels limited to 2 h daily). After termination of the 6 week exercise protocol, all rats were implanted with the telemetric electrocardiogram transmitters and were studied 1 week later. 3. Resting heart rate (HR) values in the control rats, 24 h runners and 2 h runners were 372 ± 7, 361 ± 9 and 298 ± 5 b.p.m., respectively (P < 0.05 for 2 h runners vs controls). The high-frequency spectral power in the control rats, 24 h runners and 2 h runners was 3.9 ± 0.2, 4.3 ± 0.3 and 5.3 ± 0.3 s², respectively (P < 0.05 for 2 h runners vs controls), whereas intrinsic HR was 383 ± 3, 377 ± 2 and 346 ± 3 b.p.m., respectively (P < 0.001 for 2 h runners vs controls). Restraint stress provoked tachycardia of similar magnitude in all groups. 4. After completion of telemetric studies, haemodynamic indices and susceptibility to cardiac arrhythmias were assessed in anaesthetized animals, there were no major between-group differences in HR, arterial pressure, contractility indices or sensitivity to β-adrenoceptor stimulation (dobutamine) or blockade (atenolol). The effective refractory period in the control rats, 24 h runners and 2 h runners was 49 ± 2, 55 ± 2 and 60 ± 4 ms, respectively (P = 0.054 for 2 h runners vs controls). A significantly higher dose of aconitine was required to provoke ventricular arrhythmias in the 24 h and 2 h running groups compared with controls (489 ± 76, 505 ± 88 and 173 ± 33 μg, respectively; P < 0.05). 5. We conclude that, in rats, long-term voluntary exercise has enduring cardioprotective effects mediated at the level of both the central nervous system and the heart.
Authors:
Mirza I Beig; Robin Callister; David A Saint; Eugene Bondarenko; Frederick R Walker; Trevor A Day; Eugene Nalivaiko
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Clinical and experimental pharmacology & physiology     Volume:  38     ISSN:  1440-1681     ISO Abbreviation:  Clin. Exp. Pharmacol. Physiol.     Publication Date:  2011 Jan 
Date Detail:
Created Date:  2011-01-04     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0425076     Medline TA:  Clin Exp Pharmacol Physiol     Country:  Australia    
Other Details:
Languages:  eng     Pagination:  19-26     Citation Subset:  IM    
Copyright Information:
© 2010 The Authors. Clinical and Experimental Pharmacology and Physiology © 2010 Blackwell Publishing Asia Pty Ltd.
Affiliation:
University of Newcastle, Callaghan, New South Wales, Australia.
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