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The effects of cAMP on force of contraction and recovery from fatigue of fast twitch muscle is dependent on stimulation parameters
Author(s) -
MacDonald Tara L,
Murrant Coral L
Publication year - 2012
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.26.1_supplement.1078.12
Subject(s) - stimulation , contractility , contraction (grammar) , medicine , endocrinology , inotrope , skeletal muscle , chemistry , cyclic adenosine monophosphate , muscle contraction , adenosine , muscle fatigue , biology , electromyography , receptor , neuroscience
Cyclic adenosine monophosphate (cAMP) is a potent second messenger in signal transduction and a positive inotropic regulator of cardiac muscle contractility, however effects on skeletal muscle mechanics are unclear. To determine the effect of 10 −5 M dibutyryl cAMP on post‐fatigue recovery in soleus (SOL) and extensor digitorum longus (EDL) in vitro, we stimulated SOL and EDL using varied contraction frequencies (contractions per minute; CPM) and total stimulation duration to elicit diverse fatigue profiles. SOL fatigued for 7 and 9min at 30 and 15CPM and recovered to 91.5±0.7% and 80.4±3.04% force. Long duration stimulation for 90min at 30 and 15CPM elicited 8.5±4.2% and 7.3±3.5% force restitution. SOL exposed to cAMP did not differ significantly from controls. EDL fatigued for 5 and 14 min at 10 and 2 CPM and recovered 84.1±4.1% and 81.2±1.20% force. Stimulation for 90min at 10 and 2CPM produced 7.7±1.5% and 1.2±2.9% recovery of force production. cAMP significantly improved recovery following high‐frequency stimulation (10CPM), but inhibited recovery after low‐frequency stimulation (2CPM). These results suggest that the effects of cAMP on contractility are a) fiber‐type dependent, such that only fast‐twitch fibers (EDL) respond to cAMP as an inotropic factor and b) the observed effect is dependent on stimulation parameters, namely frequency of contraction.