Systemic effects of colchicine on phosphate metabolism in innervated and denervated, slow and fast muscles of the rat.

A single systemic injection of 75 micrograms colchicine/100 g body weight increases the permeability to inorganic phosphate of both fast gastrocnemius and extensor digitorum longus muscles and of the slow soleus muscle. In the two fast muscles, there is a significant interaction between colchicine treatment and 5-d- or 30-d- surgical denervation. In the slow soleus muscle there is no interaction between 5-d-colchicine treatment and the initial decrease in phosphate flow due to 5-d-surgical denervation but a significant interaction between colchicine treatment and the secondary increase in phosphate permeability observed after a 30-d-surgical denervation. Thirty days after a single systemic injection of colchicine the muscle phosphate metabolism is still perturbed especially in the slow soleus muscle in which the initial decrease in radioactive uptake associated with a 5-d-surgical denervation is inapparent. It is proposed that colchicine induces denervation-like alterations in the Pi- and POAS metabolism of skeletal muscles through mechanisms which are also activated -- partly or entirely -- by surgical denervation. These alterations do not result from the interruption of the axonal flow. A direct effect on the muscle membrane seems less likely than a disinhibition or activation of the muscle protein synthesis system.