A glycogen assay based on bacterial NADH luciferase is described. It is free of tissue interference. The detection limit is 0.12 nmol glycogen, and the coefficient of variation is 5.5%. A method of depleting human eccrine sweat glands while retaining their viability is described. This depends on their incubation in 10(-5) M acetylcholine and 1 mM pyruvate. This method may be applicable to other tissues. The evidence for the viability of glycogen-depleted human eccrine sweat glands is reported and includes tissue contents of ATP and the rates of oxidation of glucose, pyruvate, beta-hydroxybutyrate, and palmitate.