Fig. 1.

Myoglobin expression and fiber type diversity in mice exposed to chronic hypoxic conditions. A: Western blot analysis of myoglobin expression revealed an induction of myoglobin expression in the heart in response to chronic hypoxia (10% oxygen for 0, 7, 14, and 21 days). In contrast, myoglobin expression was decreased in the resting or quiescent tibialis anterior (TA) and did not change in the weight-bearing soleus skeletal muscles. The α-tubulin expression demonstrates equal loading of all the samples. B: quantification of the myoglobin protein expression as measured by Western blot analysis in the heart, soleus, and TA muscles (n = 3 for each). Values were normalized to α-tubulin expression. C: quantification of the fiber type population in the soleus and TA muscles harvested from mice that were exposed to 3 wk of hypoxia. Note that there is no significant change in fiber type that would account for the decrease in myoglobin expression observed in the sedentary TA muscles after 3 wk of hypoxic exposure. *Significant difference between hypoxic and normoxic conditions (n = 3, P < 0.05).