Effect of D-glucose on nitric oxide release from glomerular endothelial cells.
BACKGROUND
Altered glomerular production of nitric oxide (NO) may be involved in hyperfiltration in early diabetic nephropathy. However little is known as to the role of glomerular endothelial cells (GECs) in diabetic hyperfiltration and their ability to release NO in response to hyperglycemia.


METHODS
Using an established cell line, we directly monitored NO release from GECs in response to various concentrations of D-glucose, D-mannitol, and L-arginine, an NO synthase (NOS) agonist. L-Arginine-induced NO release was examined in the cells pretreated for different periods up to 24 h with 10 or 30 mM D-glucose. We also measured serially the accumulation of nitrite, the stable metabolite of NO, produced by the cells incubated for up to 24 h under 10 or 30 mM D-glucose conditions in the presence or absence of the NOS inhibitor, L-NAME.


RESULTS
Direct measurement of NO demonstrated that D-glucose, but not D-mannitol, stimulation resulted in a rapid and dose-dependent increase in NO release by the cells. However, L-arginine-induced NO release was attenuated significantly in the cells preincubated for more than 12 h with 30 mM D-glucose compared to 10 mM D-glucose. The L-NAME-inhibitable production of nitrite in the media was significantly increased 1.5--2.0-fold until 6 h after incubation with 30 mM D-glucose compared to 10 mM D-glucose.


CONCLUSIONS
We conclude that D-glucose, but not D-mannitol, produces a rapid and dose-dependent increase in NO release, whereas exposure to high D-glucose for more than 12 h may blunt NOS activity and/or NO stability in the GECs. These observations may therefore be important for glomerular endothelial dysfunction induced by hyperglycemia that is still tentative and may have a role in diabetic nephropathy.
Kasai
N
N
Third Department of Internal Medicine, Hirosaki University School of Medicine, Hirosaki, Aomori, Japan.
Sugimoto
K
K
Horiba
N
N
Suda
T
T
D000704:Analysis of Variance; D000818:Animals; D000952:Antigens, Polyomavirus Transforming / Q000235:genetics; D001120:Arginine / Q000494:pharmacology; D002417:Cattle; D002461:Cell Line, Transformed; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D005947:Glucose / Q000494:pharmacology*; D006943:Hyperglycemia; D007678:Kidney Glomerulus / Q000098:blood supply*; D007700:Kinetics; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism; D013539:Simian virus 40 / Q000235:genetics
D000952:Antigens, Polyomavirus Transforming; D009573:Nitrites; D009569:Nitric Oxide; D001120:Arginine; D005947:Glucose; D019331:NG-Nitroarginine Methyl Ester