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Friday, June 23rd, 2017
Table of Contents

1 Introduction
5 PMID
 [F] Diseases Research  / PubMed Research Articles  /
Vasoconstrictor responsiveness in contracting human muscle: influence of contraction frequency, contractile work, and metabolic rate.

PubMed

 

Resource

European journal of applied physiology 2017 Jun 18; ()

Authors

Kruse NT1; Hughes WE2; Ueda K3; Casey DP4;

Author Information
  • 1Department of Physical Therapy and Rehabilitation Science, Carver College of Medicine, University of Iowa, Iowa, IA, 52242, USA. Nicholas-kruse-1@uiowa.edu.
  • 2Department of Physical Therapy and Rehabilitation Science, Carver College of Medicine, University of Iowa, Iowa, IA, 52242, USA.
  • 3Department of Anesthesia, Carver College of Medicine, University of Iowa, Iowa, IA, USA.
  • 4Department of Physical Therapy and Rehabilitation Science, Carver College of Medicine, University of Iowa, Iowa, IA, 52242, USA.

Abstract

PURPOSE: The aim of this study was to examine whether independent effects exist between contractile work and metabolic demand (VO2m) on vasoconstrictor responsiveness (i.e., functional sympatholysis) under different contraction durations matched for total contractile work in exercising human skeletal muscle.

METHODS: Ten young men performed rhythmic forearm contractions at 10 and 15% of maximum voluntary contraction (MVC) which consisted of muscle contractions using the same duty cycle but altering the duration of the contraction-relaxation cycles of exercise and included: 1) fast frequency contractions at 10% MVC (FFC10%) using a contraction relaxation cycle at 1:2 s; 2) slow frequency contractions at 10% MVC (SFC10%) at 2:4 s; and 3) SFC at 15% MVC (SFC15%) at 2:4 s. Lower body negative pressure (LBNP) was applied to increase sympathetic vasoconstriction during forearm exercise. Brachial artery diameter and blood velocities (measured via Doppler ultrasound) determined forearm blood flow (FBF), and forearm vascular conductance (FVC) was calculated from FBF (ml min(-1)) and mean arterial blood pressure.

RESULTS: Results revealed that steady-state indices of FBF, FVC, and VO2m were greater (P < 0.05) in FFC10% and SFC15% vs. SFC10%. In addition, the magnitude of vasoconstriction (percent reduction in FVC) in response to reflex increases in sympathetic activity during LBNP was greater with SFC10% vs. FFC10% (-20.6 ± 3.0 vs. -11.1 ± 2.0%; P < 0.05), whereas there was no difference with FFC10% vs. SFC15% (-11.1 ± 2.0 vs. -11.8 ± 1.8%; P = 0.91).

CONCLUSIONS: Our data indicate that faster work-matched muscle contractions increase blood flow and metabolism, leading to improved functional sympatholysis as compared to slower work-matched muscle contractions in humans.



PMID

28624852

Others

Publication Type: Journal Article


This article is licensed under the the National Library of Medicine License. It uses material from the PubMed National Library of Medicine Data.


Last Modified:   2016-03-27


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