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Effects of the enantiomers of R,S‐salbutamol on incompletely fused tetanic contractions of slow‐ and fast‐twitch skeletal muscles of the guinea‐pig
Author(s) -
Prior Chris,
Leonard Maureen B.,
McCullough John R.
Publication year - 1998
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1038/sj.bjp.0701627
Subject(s) - salbutamol , chemistry , guinea pig , soleus muscle , skeletal muscle , enantiomer , muscle contraction , endocrinology , medicine , stereochemistry , biology , asthma
The effects of racemic R,S ‐salbutamol, and its individual enantiomers have been studied on incompletely fused (sub‐tetanic) contractile responses of fast‐ and slow‐contracting isolated skeletal muscles of the guinea‐pig.R,S ‐salbutamol (2–4 μ M ) decreased the peak force of sub‐tetani in the slow‐contracting soleus muscle and increased the peak force of sub‐tetani in the fast‐contracting peroneus longus muscle. It also increased the force of the first twitch of sub‐tetani in both muscles. The decrease in the peak force of sub‐tetani in the soleus muscle was due to defusion of the individual twitches caused by a shortening of their time course. The effects of 4 μ M of the racemate on both fast‐ and slow‐contracting muscles were mimicked by 2 μ M R ‐salbutamol (levalbuterol). However, 2 μ M S ‐salbutamol was devoid of activity in both muscles. We concluded that all the effects of R,S ‐salbutamol on guinea‐pig skeletal muscles are due to the activity of the R ‐enantiomer. Thus there is a common enantiomeric profile for the skeletal muscle and bronchorelaxant activity of the compound.British Journal of Pharmacology (1998) 123 , 558–564; doi: 10.1038/sj.bjp.0701627