当前位置： SCI文献检索 > JOURNAL OF MUSCLE RESEARCH AND CELL MOTILITY期刊下所有文献 > Therapeutic clenbuterol treatment does not alter Ca2+ sensitivity of permeabilized fast muscle fibres from exercise trained or untrained horses.

Therapeutic clenbuterol treatment does not alter Ca2+ sensitivity of permeabilized fast muscle fibres from exercise trained or untrained horses.

Abstract：

:Clenbuterol is a beta2-adrenoceptor agonist primarily used for treating bronchospasm and alleviating the symptoms of chronic obstructive pulmonary disease (COPD) in the horse. In other species (rats, mice, sheep, and cattle), chronic high doses of clenbuterol (typically in the milligram per kilogram body weight range) has been shown to cause a muscle directed protein anabolic response. Clenbuterol can also modify muscle fibre composition and therefore potentially affect muscle function. This has implications for the performance of exercising horses being treated with therapeutic doses of clenbuterol (typically in the microgram per kilogram body weight range) for bronchospasm or COPD. It is not known whether clenbuterol treatment affects muscle fibre function in horses. The purpose of this study was to examine the effects of a therapeutic dose of clenbuterol, with and without exercise, on the contractile activation characteristics of single membrane permeabilized fibres prepared from muscle biopsies. We tested the hypothesis that therapeutic treatment with clenbuterol would not affect muscle fibre function. Unfit Standardbred mares were treated for 8 weeks with; clenbuterol (2.4 microg/kg twice/day, 5 days/week) plus exercise (20 min at 50% VO2(max) 3 d/wk; CLENEX), clenbuterol only (CLEN), or exercise only (EX). Muscle biopsies were taken from the gluteus medius muscle before and after treatment and stored in a glycerol-based solution to prepare permeabilized muscle fibres. The force-pCa relationship for fibres from CLEN horses was steeper (P < 0.05) indicative of greater cooperative interactions within the thin filament, however, fibre sensitivity to Ca2+ was unchanged. In contrast, the steepness of the force-pCa relationship was not changed in fibres from EX and CLENEX horses and Ca2+ sensitivity was also unaffected. Rigor force, activation in the absence of ATP, was not affected by any treatment indicating an approximately equivalent number of participating cross-bridges during activation. The results indicate that a therapeutic dose of clenbuterol to Standardbred horses does not affect the Ca(2+)-activated contractile characteristics of isolated muscle fibres.

journal_name

J Muscle Res Cell Motil

journal_title

Journal of muscle research and cell motility

authors

Plant DR,Kearns CF,McKeever KH,Lynch GS

doi

10.1023/a:1027377731137

keywords:

subject

Has Abstract

pub_date

2003-01-01 00:00:00

pages

471-6

issue

eissn

0142-4319

issn

1573-2657

journal_volume

pub_type

杂志文章

在线工具

Therapeutic clenbuterol treatment does not alter Ca2+ sensitivity of permeabilized fast muscle fibres from exercise trained or untrained horses.