Under the local ischemia, the supply of sufficient oxygen and energy sources such as free fatty acid and glucose become difficult. This also affects the electrical properties of a cell membrane and it seems to be also concerned in action potential propagation velocity on the muscle fibre. In order to measure muscle function under the local ischemia, an intramuscular probe and measurement system were developed. This probe is composed of optical fiber which measures blood flow and 10 platinum fine electrodes for the action potential measurement. In gastrocnemius of rat, the action potential and blood flow were measured using this probe. The popliteal artery was ligated, and tibial nerve was electro-stimulated. With the advance of the ischemia, the potential propagation velocity, which was calculated from action potential wave got between two electrodes, gradually decreased after the ligation. In all cases of several experiments, the propagation velocity was decreased.