Fig 6. Stimulation and inhibition of sweat gland cells monitored with calcium indicator fluo-4.

(A) Fluorescence levels (ΔF/F0) in 3D SG models derived from facial or axillary sweat glands show stimulation and inhibition of receptors/ion channels in 3D SG models with fluo-4 (Student’s t-test with n = 6; mean±SEM; p<0,05(*)<0,01(**)). Muscarinic receptor (mAChR) agonists (ACh, pilocarpine) and purinergic stimulation (ATP) increased intracellular Ca²⁺-levels, but remarkably significant in axillary 3D SG models. Muscarinic antagonist, glycopyrrolate, inhibits stimulation with ACh only in axillary 3D SG models. (B) Schema of key receptors and target ion channels in secretory clear cells involved in sweat secretion. Ca²⁺ influx mediated by channels in endoplasmic reticulum (ER) and by ORAI/TRPC channels in plasma membrane.