The clear cell of the eccrine secretory coil actively transports sodium into the intercellular canaliculus. As a result of the osmotic gradient, water flows across the cell from the extracellular fluid to restore osmotic equilibrium; an isotonic secretory fluid is, thus, elaborated. The energy source for this active secretory process is mainly derived from the aerobic glycolysis of glucose. Glucose metabolism of isolated sweat glands in vitro can be stimulated by both cholinergic and adrenergic drugs and inhibited by ouabain. This suggests that glucose metabolism and active sodium transport are closely linked within the secretory cells.
Dobson RL, Sato K. The Secretion of Salt and Water by the Eccrine Sweat Gland. Arch Dermatol. 1972;105(3):366-370. doi:10.1001/archderm.1972.01620060008002