Contractile properties of EDL and soleus muscles of myostatin-deficient mice

doi:10.1152/japplphysiol.00126.2006.— Myostatin is a negative regulator of muscle mass. The impact of myostatin deficiency on the contractile properties of healthy muscles has not been determined. We hypothesized that myostatin deficiency would increase the maximum tetanic force (Po), but decrease the specific Po (sPo) of muscles and increase the susceptibility to contrac-tion-induced injury. The in vitro contractile properties of extensor digitorum longus (EDL) and soleus muscles from wild-type (MSTN/), heterozygous-null (MSTN/), and homozygous-null (MSTN/) adult male mice were determined. For EDL muscles, the Po of both MSTN/ and MSTN/ mice were greater than the Po of MSTN/ mice. For soleus muscles, the Po of MSTN/ mice was greater than that of MSTN/ mice. The sPo of EDL muscles of MSTN/ mice was less than that of MSTN/ mice. For soleus muscles, however, no difference in sPo was observed. Following two lengthening contrac