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Stimulation pattern independent and dependent release of vasodilators during skeletal muscle contraction
Author(s) -
Dua Ashok K,
Murrant Coral L
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a273-a
Subject(s) - contraction (grammar) , chemistry , skeletal muscle , stimulation , muscle contraction , hamster , medicine , biophysics , endocrinology , biology
To determine if the vasodilators produced during contraction are dependent on stimulation parameters we stimulated 4–5 muscle fibers (for 2 min, 250ms train duration) in an anesthetized hamster cremaster in situ and measured changes in diameter of arterioles (max diameter ≅40um) at the site overlap with stimulated muscle fibers. Muscle was stimulated at contraction frequencies of 6, 12 or 60 contractions per minute (CPM)(stimulus frequency 20Hz) or stimulus frequencies of 4, 20 or 40Hz (contraction frequency 12CPM) in the absence and presence of a K ATP channel inhibitor glybenclamide (Gly, 10 −5 M) or an adenosine receptor antagonist xanthine amine congener (XAC, 10 −6 M). Data is expressed as % decrease from control at 120sec. Both Gly and XAC significantly inhibited dilations at all contraction frequencies (for 6, 12 and 60CPM respectively: for Gly: 114.6+2.5%, 93.9+2.6% and 48.2+7.3%; for XAC: 142.8+8%, 102.3+1.9% and 70.1+1.9%) where the magnitude of the inhibitions decreased as contraction frequency increased. Both Gly and XAC significantly inhibited dilations at all stimulus frequencies (for 4, 20 and 40Hz respectively: for Gly: 101.3+2.5%, 93.9+ 2.6%, and 100.2+ 1.1%; for XAC: 147.4+12%, 102.3+1.9%, and 53.7+ 4.3%) but the magnitude of the inhibitions were not significantly different from each other with Gly but were significantly different from each other with XAC. Therefore the amount of K ATP channel activation during skeletal muscle contraction is dependent on contraction frequency but independent of stimulus frequency. The release of adenosine is dependent on both stimulus and contraction frequency. Supported by NSERC and PREA.