Potassium accumulation in the frog spinal cord induced by nociceptive stimulation of the skin.

Changes of extracellular K+ concentration (delta[K]e) were studied in the frog spinal cord in response to noxious skin stimulation by hot water (55-65 degrees C). The magnitude of delta[K]e was dependent on the duration and the extent of the skin area heated. The maximum of delta[K]e (0.2-1.0 mmol X 1(-1)) occurred in the dorsal horn at about the same location where the highest increase of [K]e was observed in response to electrical stimulation of the skin. The nociceptive as well as electrical stimulation of contralateral hindlimb resulted in delta[K]e, which was about 50% of that observed during ipsilateral stimulation.