Micropuncture and microperfusion study of glucose excretion in rat parotid saliva

The handling of glucose and glucose ¹⁴C was studied in the rat parotid using micropuncture and microperfusion techniques. Glucose and glucose ¹⁴C concentrations were measured directly in the plasma and final saliva, and glucose ¹⁴C was measured in the fluid obtained from the intercalated ducts. In addition, the glucose ¹⁴C and 3 O ¹⁴C methyl D glucose content of the intracellular water of the gland was calculated and the main duct of the parotid was perfused with saliva containing glucose ¹⁴C and inulin ³H. The results of this study show that permeability or transport barriers for glucose exist on both the contraluminal and luminal sides of the secretory cells of the rat parotid; the primary secretory fluid contains glucose in concentrations ranging from 20 to 5% of the concentrations in the intracellular water or plasma water; the excretory ducts of the gland which are impermeable to water are also impermeable to glucose.