Calcium ion gradients and dynamics in cultured skin slices of rat hindpaw in response to stimulation with ATP.

Ionotropic receptors, originally found in the brain, were recently also identified in epidermal keratinocytes. Moreover, concentration gradients and movement of calcium are crucial in epidermal homeostasis. Thus, imaging of calcium in the living epidermis is expected to provide insight into epidermal physiology and pathology. Here we describe the imaging of calcium dynamics in the living epidermis of cultured skin slices. The basal calcium concentration was highest in the upper layer of the epidermis. The increase of intracellular calcium in response to adenosine triphosphate (ATP) varied in each layer of epidermis, and was greater at the bottom than in the uppermost layer. Further, the extent of elevation of intracellular calcium in response to ATP in cultured keratinocytes varied depending on the level of differentiation. These results suggest that the response to stimulation of keratinocytes in cultured skin slices varies depending upon the location (depth) within the epidermis.