Document Detail


Exercise training causes skeletal muscle venular growth and alters hemodynamic responses in spontaneously hypertensive rats.
MedLine Citation:
PMID:  11393677     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
OBJECTIVE: To investigate whether training changes skeletal muscle venular profile and hemodynamic responses to exercise we studied spontanesouly hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats submitted to training programme (T = 50-60% of VO2max). DESIGN: Training (T) was performed on a treadmill over a period of 13 weeks. Age-matched control groups were kept sedentary (S). T and S rats were chronically instrumented for hindlimb flow (HLF) and arterial pressure (AP) measurements at rest, during dynamic exercise and recovery in two different situations: control and after extensive intravenous blockade (hexamethonium + losartan + Nomega-nitro-L-arginine methyl ester + hydralazine). For morphometric analysis, skeletal muscle samples (gracilis) were obtained after transcardiac perfusion with fixative. RESULTS: T caused a significant reduction of resting mean arterial pressure (MAP) (-11%) only in the SHR group without changing basal HLF. In the sedentary SHR (SHRs), basal relative hindlimb resistance was increased by 45%, but was significantly reduced after T (P < 0.05). During dynamic exercise, MAP increased similarly (10-20 mmHg) in all groups. HLF increases were similar for the four groups up to 0.8 km/h; at higher workloads, HLF was higher in trained SHR (SHRT) versus trained WKY (WKYT) (3.9- versus 2.9-fold increase over basal HLF, respectively). After blockade (and pressure correction with IV phenylephrine infusion), steady-state exercise was performed with similar hindlimb vasodilation in all groups and was accompanied by MAP reduction (-17 +/- 8 mmHg) only in SHRT group. Skeletal muscle venular profile (density, diameter and lumen cross-sectional area) was similar in WKY(T), WKY(S) and SHR(S), but significantly increased in SHR(T). In this group the two-fold increase in venule density was correlated with both the reduction in baseline MAP and the increase in HLF during dynamic exercise. CONCLUSIONS: The results suggest that increased venule density is a specific adaptation of SHR skeletal muscle to training. Venular growth may contribute to both the pressure-lowering effect and the large HLF at high exercise intensities observed in the trained SHR.
Authors:
S L Amaral; N P Silveira; T M Zorn; L C Michelini
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of hypertension     Volume:  19     ISSN:  0263-6352     ISO Abbreviation:  J. Hypertens.     Publication Date:  2001 May 
Date Detail:
Created Date:  2001-06-06     Completed Date:  2001-10-18     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  8306882     Medline TA:  J Hypertens     Country:  England    
Other Details:
Languages:  eng     Pagination:  931-40     Citation Subset:  IM    
Affiliation:
Department of Physiology and Biophysics, ICB, University of São Paulo, Brazil.
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MeSH Terms
Descriptor/Qualifier:
Animals
Hemodynamics / physiology*
Hindlimb / blood supply
Hypertension / pathology,  physiopathology*
Male
Muscle, Skeletal / blood supply*,  pathology
Physical Conditioning, Animal*
Rats
Rats, Inbred SHR / physiology*
Rats, Inbred WKY
Reference Values
Regional Blood Flow / physiology
Venules / growth & development

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


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