Extracellular potassium concentration in normal and denervated hind limb muscles of the rat

K+-sensitive electrodes with a side pore were used for measuring extracellular potassium levels in control muscles and in the gastrocnemius, extensor digitorum and soleus muscles of the rat, one, 8 and 14 days after denervation. In all cases, the extracellular potassium level was close to 5 mmol.1-1. There were no substantial differences between muscles of different functional and morphological types and between control and denervated muscles. Elevated extracellular potassium cannot therefore be the reason for increased sensory outflow of impulses observed after motor denervation.