Fig 1.
Western blot (a) and RT-PCR (b) of sodium glucose cotransporter 2.
The IgG antibody reacted with membrane proteins of the appropriate predicted molecular weight (73 kDa) from both mesangial cells (left) and renal proximal tubular epithelial cells (right). RT-PCR products for SGLT2 from the total RNA from both mesangial cells (A: left) and renal proximal tubular epithelial cells (B: right) revealed a single band of the appropriate predicted size (422 bp).
Fig 2.
Serial changes in the cell surface area at different glucose concentrations.
▲: 2.5 mM glucose, ○: 5 mM glucose, □: 5 mM glucose + mannitol, ●: 10 mM glucose, ■: 20 mM glucose. n = 6 in each condition. Data are the mean ± SD. Changes in surface area were measured every 20 min. *: p<0.05 vs 5 mM glucose for the same period, **: p<0.01 vs 5 mM glucose for the same period.
Fig 3.
Effects of extracellular sodium and calcium on cellular contraction.
Cell surface area was determined after a 60 min incubation in the presence (NaCl) and absence (choline-Cl) of sodium and calcium. n = 6 in each condition. Data are the mean ± SD. *: p<0.001 vs 5 mM glucose.
Fig 4.
Effects of non-metabolizable sugars on cellular contraction.
Cell surface area was determined after exposure for 60 min to conditioned media. AMG: 15 mM α-methyl-glucoside, mannitol: 15 mM mannitol, 2DOG: 15 mM 2-deoxy-glucose. n = 6 in each condition. Data are the mean ± SD. *: p<0.005 vs 5 mM glucose.
Fig 5.
Inhibitory effect of the sodium-coupled glucose transporter and the Na+/Ca2+ exchanger on glucose-induced cellular contraction.
Cell surface area was determined after 60 min of exposure to conditioned media. n = 6 in each condition. Data are the mean ± SD. *: p<0.001 vs 5 mM glucose.
Fig 6.
Effects of a calcium channel blocker on glucose-induced cellular contraction.
Cell surface area was determined after 60 min of exposure to conditioned media with either 5 mM glucose, 20 mM glucose or 10-7 M angiotensin II in the presence (□) or absence (■) of nicardipine. n = 6 in each condition. Data are the mean ± SD. *: p<0.05 vs 5 mM glucose. #: p<0.001 vs 20 mM glucose with and without nicardipine.
Fig 7.
Time-resolved measurements of the cellular size of rat mesangial cells incubated with various conditions for up to 6 days.
□: 5 mM glucose, ■: 5 mM glucose with 10-7 M phlorizin, ○: 20 mM glucose, ●: 20 mM glucose with 10-7 M phlorizin. Determination of cellular size was repeated in different rat mesangial cell preparations, measuring more than 100 cells in each condition. The data are the mean ± SD. *: p<0.01 vs 5 mM glucose.
Fig 8.
The contractile response to angiotensin II in rat mesangial cells incubated with 5 mM and 20 mM glucose with or without phlorizin for 6 days.
n = 6 in each condition. The data are the mean ± SD. *: p<0.01 vs 5 mM glucose.
Fig 9.
Schematic representation of the effect of SGLT2 on mesangial cells.
Glucose enters the cells through both a facilitative glucose transporter (GLUT1) and a sodium-coupled glucose transporter 2 (SGLT2). Na+ entry through SGLT2 according to extracellular glucose concentrations brings about Ca2+ influx through the sodium-calcium exchanger (NCX), which induces cellular contraction.