High glucose enhances growth factor-stimulated nitric oxide production by cultured rat mesangial cells.
Nitric oxide (NO) contributes to the alterations in glomerular hemodynamics and extracellular matrix accumulation observed in diabetic nephropathy. High glucose concentrations directly inhibit NO production by rat mesangial cells (RMC). However, the role of peptide growth factors and chemokines in regulating NO synthesis by RMC under normal and high glucose conditions has not been studied. Therefore, we examined the effect of IGF-I, EGF, TGF-beta and RANTES on NO production by RMC maintained in normal (5.6 mM) or high glucose (33.3 mM) for 48 h. No synthesis was determined by measuring nitrite accumulation in conditioned media with the Greiss reaction. In normal glucose media, IGF-I, EGF, and RANTES had no effect on nitrite accumulation while TGF-beta inhibited NO synthesis. In high glucose conditions, IGF-I and EGF significantly enhanced NO production. The effects of RANTES and TGF-beta were unchanged by an elevated glucose concentration. EGF-induced stimulation of NO production in high glucose media was associated with parallel alterations in iNOS gene and protein expression. The modest enhancement in nitrite accumulation provoked by IGF-I in high glucose conditions was not accompanied by demonstrable increases in iNOS mRNA abundance or protein content. In conclusion, peptide growth factors modulate the direct inhibitory effect of high glucose on NO production by cultured mesangial cells. These actions in vivo may limit the adverse consequences of reduced NO production in promoting diabetic nephropathy.
Division of Nephrology, Schneider Children's Hospital, Long Island Jewish Medical Center, New Hyde Park, NY 11040-1432, USA.
H
H
Trachtman
I
I
Koss
M
M
Bogart
J
J
Abramowitz
S
S
Futterweit
N
N
Franki
P C
PC
Singhal
D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D002470:Cell Survival; D002478:Cells, Cultured; D018946:Chemokine CCL5 / Q000494:pharmacology; D017077:Culture Media, Conditioned; D003928:Diabetic Nephropathies / Q000209:etiology; D004815:Epidermal Growth Factor / Q000494:pharmacology; D005920:Glomerular Mesangium / Q000187:drug effects*; D005947:Glucose / Q000032:analysis*; D006133:Growth Substances / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000737:chemistry / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D016212:Transforming Growth Factor beta / Q000494:pharmacology
D018946:Chemokine CCL5; D017077:Culture Media, Conditioned; D006133:Growth Substances; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D009569:Nitric Oxide; D004815:Epidermal Growth Factor; D007334:Insulin-Like Growth Factor I; D019001:Nitric Oxide Synthase; D005947:Glucose