867 Contraction of myoepithelial cells in human eccrine sweat glands, revealed by 3D live imaging

Abstract

Sweat glands are single tubular organs subdivided into two parts: excretory and secretory ducts, both of which form a complicated coiled structure in the deep dermis. Secretory ducts are surrounded by contractile myoepithelial cells. Contraction of these myoepithelial cells is thought to contribute to the secretion of sweat. However, it remains unknown whether sweat gland myoepithelial cells contract. We previously revealed that myoepithelial cells were aligned in a well-oriented manner, enabling efficient contraction of secretory ducts, which likely facilitates sweat excretion. Human sweat gland dynamics were captured using a live-imaging system with actin, nuclear, and cell membrane markers. The contraction of myoepithelial cells was induced by pilocarpine, an acetylcholine analogue. Live-imaging data revealed that a portion of the secretory duct began to contract in the direction of narrowing tube diameter, immediately after pilocarpine addition; this was followed by gradual distention of two distal excretory ducts. The contractile motion of the coiled tubular components of the sweat gland showed sequential contraction, enabling transportation of sweat. Moreover, this contraction was inhibited by the sweating antagonist, atropine. These results suggest that myoepithelial cell contraction may be necessary to generate the driving force for transporting the sweat. We plan to further analyze the kinetics of myoepithelial contracting motion, in combination with pharmacological intervention, to identify the specific regulatory mechanisms involved.