A constitutive nitric oxide synthase modulates insulin secretion in the INS-1 cell line.
We provide immunocytochemical evidence that the neuronal isoform of constitutive NO synthase (cNOS) is expressed in the rat insulinoma cell line INS-1. Furthermore, using N omega-nitro-L-arginine methyl ester (L-NAME), a pharmacological inhibitor of cNOS activity, we show that this enzyme is implicated in the modulation of insulin secretion in INS-1 cells. Indeed, in the presence of 2.8 mM glucose, L-NAME induced a specific and dose-dependent increase in insulin release, suggesting that cNOS exerts an inhibitory tone on basal insulin secretion. Moreover, L-arginine, the physiological substrate of cNOS, significantly reduced the marked enhancing effect of L-NAME on insulin release and to a lesser extent, at low concentrations, that of 10 mM KCl. L-NAME also potentiated the insulin secretion stimulated by 5.5 and 8.3 mM glucose, but in this case, its effect was not reduced by L-arginine. In conclusion, our data show that the neuronal isoform of cNOS exerts a negative modulation on insulin secretion in INS-1 cells, confirming the previous results obtained in the isolated perfused rat pancreas or pancreatic islets.
Beffy
P
P
Istituto di Mutagenesi e Differenziamento, CNR, Pisa, Italy.
Lajoix
A D
AD
Masiello
P
P
Dietz
S
S
Péraldi-Roux
S
S
Chardès
T
T
Ribes
G
G
Gross
R
R
D000818:Animals; D001120:Arginine / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007340:Insulinoma; D007527:Isoenzymes / Q000378:metabolism; D008856:Microscopy, Fluorescence; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology*; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052248:Nitric Oxide Synthase Type I; D010190:Pancreatic Neoplasms; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D013386:Succinates / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D004791:Enzyme Inhibitors; D007328:Insulin; D007527:Isoenzymes; D013386:Succinates; D009569:Nitric Oxide; D011189:Potassium Chloride; D001120:Arginine; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; C496322:Nos1 protein, rat; C039138:methylsuccinic acid; D005947:Glucose; D019331:NG-Nitroarginine Methyl Ester