Iontophoresis of Potassium for Experimental Determination of Pain Endurance in Man.

Release of intracellular potassium is considered the physiological stimulus of pain production in tissue injury. Iontophoresis simulates this physiological mechanism. Therefore, it is specifically a painful stimulus. It is well controlled. The intensity of the stimulus corresponds to the intensity of pain sensation. It gives reproducible values and it causes a minimal degree of tissue damage. Therefore, iontophoresis is well suited for pain endurance measurements. However, it will not simulate the threatening content of clinical pain. Experimental data indicate that day to day variability in the same subject is small, while differences between subjects and between groups may be large.