¹Shiseido Research Center, Shiseido Co., Ltd., Yokohama, Japan

Correspondence: Dr Mitsuhiro Denda, Shiseido Research Center, 2-12-1, Fukuura, Kanazawa-ku, Yokohama 236-8643, Japan. E-mail: mitsuhiro.denda@to.shiseido.co.jp

Received 7 January 2008; Revised 29 July 2008; Accepted 2 August 2008; Published online 2 October 2008.

Abstract

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 adinosine 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.