Document Detail


The benefits of endurance training in cardiomyocyte function in hypertensive rats are reversed within four weeks of detraining.
MedLine Citation:
PMID:  23376037     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
The aim of the present study was to verify the effects of low-intensity endurance training and detraining on the mechanical and molecular properties of cardiomyocytes from spontaneously hypertensive rats (SHRs). Male SHRs and normotensive control Wistar rats at 16-weeks of age were randomly divided into eight groups of eight animals: NC8 and HC8 (normotensive and hypertensive control for 8 weeks); NT8 and HT8 (normotensive and hypertensive trained at 50-60% of maximal exercise capacity for 8 weeks); NC12 and HC12 (normotensive and hypertensive control for 12 weeks); NDT and HDT (normotensive and hypertensive trained for 8 weeks and detrained for 4 weeks). The total exercise time until fatigue (TTF) was determined by a maximal exercise capacity test. Resting heart rate (RHR) and systolic arterial pressure (SAP) were measured. After the treatments, animals were killed by cervical dislocation and left ventricular myocytes were isolated by enzymatic dispersion. Isolated cells were used to determine intracellular global Ca(2+) ([Ca(2+)](i)) transient and cardiomyocyte contractility (1 Hz; ~25ºC). [Ca(2+)](i) regulatory proteins were measured by Western blot, and the markers of pathologic cardiac hypertrophy by quantitative real-time polymerase chain reaction (q-RT-PCR). Exercise training augmented the TTF (NC8, 11.4 ± 1.5 min vs. NT8, 22.5 ± 1.4 min; HC8, 11.7 ± 1.4 min vs. HT8, 24.5 ± 1.3 min; P<0.05), reduced RHR (NT8initial, 340 ± 8 bpm vs. NT8final, 322 ± 10 bpm; HT8initial, 369±8 bpm vs. HT8final, 344 ± 10 bpm; P<0.05), and SBP in SHR animals (HC8, 178 ± 3 mmHg vs. HT8, 161 ± 4 mmHg; P<0.05). HC8 rats showed a slower [Ca(2+)](i) transient (Tpeak, 83.7 ± 1.8 ms vs. 71.7 ± 2.4 ms; T50%decay, 284.0 ± 4.3 ms vs. 264.0 ± 4.1 ms; P<0.05) and cell contractility (Vshortening, 86.1 ± 6.7 μm/s vs. 118.6 ± 6.7 μm/s; Vrelengthening, 57.5 ± 7.4 μm/s vs. 101.3 ± 7.4 μm/s; P<0.05), and higher expression of ANF (300%; P<0.05), skeletal α-actin (250%; P<0.05) and a decreased α/β-MHC ratio (70%; P<0.05) compared to NC8. Exercise training increased [Ca(2+)](i) transient (NC8, 2.39 ± 0.06 F/F(0) vs. NT8, 2.72 ± 0.06 F/F(0); HC8, 2.28 ± 0.05 F/F(0) vs. HT8, 2.82 ± 0.05 F/F(0); P<0.05), and cell contractility (NC8, 7.4 ± 0.3 % vs. NT8, 8.4 ± 0.3 %; HC8, 6.8 ± 0.3 % vs. HT8, 7.8 ± 0.3 %; P<0.05). Furthermore, exercise normalized the expression of ANF, skeletal α-actin, and the α/β-MHC ratio in HT8 rats, augmented the expression of SERCA2a (NC8, 0.93 ± 0.15 vs. NT8, 1.49 ± 0.14; HC8, 0.83 ± 0.13 vs. HT8, 1.32 ± 0.14; P<0.05) and PLB(ser16) (NC8, 0.89 ± 0.18 vs. NT8, 1.23 ± 0.17; HC8, 0.77 ± 0.17 vs. HT8, 1.32 ± 0.16; P<0.05), and reduced PLBt/SERCA2a (NC8, 1.21 ± 0.19 vs. NT8, 0.50 ± 0.21; HC8, 1.38 ± 0.17 vs. HT8, 0.66 ± 0.21; P<0.05). However, all these adaptations returned to sedentary values within 4 weeks of detraining in both SHR and normotensive control animals. In conclusion, low-intensity endurance training induces positive benefits to left ventricular myocyte mechanical and molecular properties, which are reversed within 4 weeks of detraining.
Authors:
Miguel Araujo Carneiro-Júnior; Judson Fonseca Quintão-Júnior; Lucas Rios Drummond; Victor Neiva Lavorato; Filipe Rios Drummond; Marco Aurélio Amadeu; Leonardo Bonato Felix; Edilamar Menezes de Oliveira; Jader Santos Cruz; Thales Nicolau Prímola-Gomes; José Geraldo Mill; Antonio José Natali
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2013-1-30
Journal Detail:
Title:  Journal of molecular and cellular cardiology     Volume:  -     ISSN:  1095-8584     ISO Abbreviation:  J. Mol. Cell. Cardiol.     Publication Date:  2013 Jan 
Date Detail:
Created Date:  2013-2-4     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0262322     Medline TA:  J Mol Cell Cardiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2012. Published by Elsevier Ltd.
Affiliation:
Department of Physiological Sciences, Federal University of Espírito Santo (UFES), Vitória, Espírito Santo, Brazil.
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