Effect of Methylene Blue on pyridine nucleotides and insulin secretion of rat pancreatic islets.
Methylene Blue, which is known to oxidise NADPH in red blood cells, was used to assess a possible role of NADPH in the glucose-stimulated secretion of insulin. When islets from rats were incubated with 3 mg/ml of glucose, Methylene Blue (0.5), 1.0, 2.0 or 5.0 micrograms/ml) significantly decreased the concentration of NADPH, increased that of NADP+ and decreased the NADPH/NADP+ ratio in a dose-dependent manner. This effect was associated with inhibition of the glucose-induced insulin release. No significant change of NADH, NAD+ and ATP could be observed. It is suggested that the secretory response of the pancreatic islet to glucose stimulation depends on the NADPH/NADP+ ratio.
D000818:Animals; D004305:Dose-Response Relationship, Drug; D005260:Female; D005947:Glucose / Q000494:pharmacology; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008751:Methylene Blue / Q000494:pharmacology*; D009243:NAD / Q000378:metabolism*; D009249:NADP / Q000378:metabolism*; D010084:Oxidation-Reduction; D051381:Rats
D007328:Insulin; D009243:NAD; D009249:NADP; D005947:Glucose; D008751:Methylene Blue