ABSTRACT
<p><b>OBJECTIVE</b>To evaluate the effect of stretch on sarco(endo)plasmic reticulum Ca2+-Mg2+ ATPases activity and mRNA level and study the remodeling reaction of muscle in a variety of mechanical environments.</p><p><b>METHODS</b>Myoblast from maxillofacial skeletal muscle of one-week-old male Sprague-Dawley rat was cultured and stretched cyclicly using a four-point bend device. Inorganic Phosphorus test was used to compare the activity of Ca2+-Mg2+ ATPases of myoblast before and after stretch. RT-PCR was also used to observe the Ca2+-Mg2+ ATPases mRNA level.</p><p><b>RESULTS</b>The activity of Ca2+-Mg2+ ATPases of myoblast down regulated significantly in 4 hours. During the period of 8 hours to 24 hours, up-regulation followed then returned to control level at the 48 hour point. RT-PCR showed that Ca2+-Mg2+ ATPases mRNA level were elevated by stretch, particularly at 2 hour and 48 hour point.</p><p><b>CONCLUSION</b>The results suggested a transcriptional control of Ca2+-Mg2+ ATPases activity was involved in the muscle remodeling process induced by stretch.</p>
