We studied the effect of adrenalectomy on an experimental myopathy which is characterized by subtle morphologic alteration and profound enzyme efflux in rats. Adrenalectomy greatly reduced (by > 85%) the increase in plasma creatine phosphokinase activity and myofibrillar disruption which follow treatment with phencyclidine and restraint. Adrenal demedullation had an identical effect. A single replacement dose of epinephrine in the adrenal-demedullated rat restored the myopathic response. Denervation and β-adrenergic receptor blockade similarly prevented the development of the myopathy. These findings suggest that intense muscle activity, with increased demand for oxygen, can produce extensive architectural changes and elevate plasma creatine phosphokinase activity when adrenal epinephrine is present, perhaps via the calorigenic effect, increasing the rate of oxygen utilization, or via well known effects of epinephrine on neuromuscular transmission or contraction.
ASJC Scopus subject areas
- Developmental Neuroscience