1 Effect of aquaporin on paracellular water transport in the submandibular gland acini

Abstract

I examined the influence of aquaporin 5 (AQP 5) on paracellular water transport in submandibular gland acini using male Wistar rats weighing 250-280g. In unstimulated cells, immunoelectron staining detected AQP 5 on the luminal membrane, and ZO-1 on the lateral membrane. After parasympathetic stimulation, both AQP 5 and ZO-1 were distributed on the luminal membrane, lateral membrane and secretory granules. AQP 5 treatment of the lateral membrane increased tight junctional permeability. Because water-rich fluid was secreted in the lumen of the acinar cells where AQP 5 and ZO-1 were both abundantly present, it is reasonable to speculate that both intercellular and intracellular transport play important roles in water secretion.