Water transport by glucose transporter type 3 expressed in Xenopus oocytes.

Department of Dental Anesthesiology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Japan. tomioka@dent.tokushima-u.ac.jp

Neuroreport 2012 Jan 4

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The hypothesis that the facilitative glucose transporter type 3 (GLUT3) in the brain also exhibits water channel properties similar to that of GLUT1 was tested in Xenopus oocytes expressing human GLUT3 or GLUT1. The volume of oocytes expressing GLUT3 exposed to hypotonic medium increased in an exponential manner. The osmotic water permeability (Pf) for GLUT3 or GLUT1 increased significantly compared with that for oocytes-injected water. The osmotic water transport by GLUT3 was completely inhibited by treatment with a selective GLUT inhibitor, cytochalasin B. The Pf values for GLUT3 significantly increased with increasing temperature of the extracellular medium and the activation energy for GLUT3 was almost the same as that for GLUT1. Thus, GLUT3 in the brain also exhibits water channel properties.