Effect of muscle creatine content manipulation on contractile properties in mouse muscles

✍ Scribed by Bert O. Eijnde; Jean Lebacq; Monique Ramaekers; Peter Hespel

• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: English
• Weight: 117 KB
• Volume: 29
• Category: Article
• ISSN: 0148-639X
• DOI: 10.1002/mus.10568

✦ Synopsis

Abstract

The effects of muscle creatine manipulation on contractile properties in oxidative and glycolytic muscles were evaluated. Whereas control mice (NMRi; n = 12) received normal chow (5 g daily), three experimental groups were created by adding creatine monohydrate (CR group; 5%, 1 week; n = 13); β‐guanidinoproprionic acid, an inhibitor of cellular creatine uptake (β‐GPA group; 1%, 2 weeks; n = 12); or CR following β‐GPA (β‐GPA+CR group; n = 11). Total creatine (TCr) and the contractile properties of incubated soleus and extensor digitorum longus (EDL) muscles were determined. For the soleus, compared with control, TCr increased in the CR group (+25%), decreased in β‐GPA group (−50%), and remained stable in the β‐GPA+CR group, whereas, for the EDL, TCr was similar in the CR, and lower in the β‐GPA (−40%) and β‐GPA+CR (−15%) groups. None of the experimental groups (CR, β‐GPA, or β‐GPA+CR) showed changes in peak tension (P~peak~), time to peak tension, or relaxation in soleus or EDL during twitch or tetanic stimulation. For the soleus, fatigue reduced P~peak~ to ∼60% of initial P~peak~; 5 min of recovery restored P~peak~ to values ∼15% higher in CR than in controls. P~peak~ recovery was not affected by β‐GPA or β‐GPA+CR in the soleus or any treatment in the EDL. Thus, peak tension recovery is enhanced by creatine intake in oxidative but not glycolytic muscles. This may be implicated in the beneficial action of creatine loading. Muscle Nerve 29: 428–435, 2004