|Budget Amount *help
¥1,900,000 (Direct Cost : ¥1,900,000)
Fiscal Year 1993 : ¥800,000 (Direct Cost : ¥800,000)
Fiscal Year 1992 : ¥1,100,000 (Direct Cost : ¥1,100,000)
Glucose is one of the major nutrients in the body, and plays important roles as a substrate for various enzymatic rezctions. Glucose is distributed throughout the body by blood circulation. Most cells are freely accessible to blood glucose thanks to the high permeability of blood vessel walls. In some specialized tissues and organs in the mammlian body, however, the blood-tissue barrier exist. Here glucose must cross the barrier with the glucose transport system. To investigate the molecular machinery in such system, I made antibodies against glucose transporters, and localized the transporter proteins in the barriers. In the placental barrier and bloodaqueous barrier in the rat, couble-layr of epithelial cells constitute the barrier. GLUT1, an glucose transporter isoform specifically enriched in the barrier, was localized at the plasma membrane facing insede and outside the barrier. Numerous gap junctions connect two epothelial cell layrs. In the rat placental barrier, connexin26, an isoform of gap junction protein, was found in the junctions of two syncytial layrs. It is concluded that glucose is transported through the barrier in the following sequence : GLUT1 at the plasma membrane facing outside the barrier, cytoplasm of the first cell layr, connexin26, cytoplasm of the second cell layr, GLUT1 at the plasma membrane facing inside the barrier.