I'm studyng the effects of a new molecule on beta-cell function. I have demonstrated that it is able to increase both insulin content (glucose concentration in the medium was 11 mmol/l) and glucose-stimulated insulin secretion (25 mmol/l glucose versus 3 mmol/l glucose). Can I conclude that the molecule enhances GSIS or I have to consider that the increase of GSIS is the result of increased insulin content?
Thanks
Dear Swati,
Perhaps I did not explain. I mesuared insulin content in the whole protein extract of beta cell. I simply said that the glucose concentration in the medium was 11 mmol/l.
Regards
Nicola
Hi Nicola!
I think that your conclusion wouldn't be wrong. Your molecule is actually increasing GSIS. Probably your concern is whether the increase in GSIS is a consequence of increased insulin content or whther your molecule is actually improving the mechanisms of secretion. Probably to answer this you could measure calcium levels in beta cells when they are stimulated with glucose. Another think you could do is to check the gene expression of genes related with the secretory function. I am not an expert here, but I would check calcium channels, chromogranins, snares, synaptogamins, and check the literature for other important genes.
Hope I could help.
Good luck!
Joan
Hi Joan. Thank you for your answer. I think your suggestion are very intresting.
Dear Nicole,
First of all insulin secretion and action may be closely related but do not mean same thing. You can rationalize this fact if you look at the condition of hyperinsulinemia due to insulin resistance in the development of type 2 diabetes. It is very possible that your extract enhanced glucose induced insulin secretion from your experimental design and results. However you can further validate this by measuring intracellular ATP and Ca2+/k+ ratio or Ca2+ levels. These ions levels can be measured using flame photometry. Conventionally these parameters should increase to induce insulin release from the Beta-cells. This is because, when extracellular glucose increases, it enters the Beta-cell to produce ATP. This in turn results in the closing of K+ membrane pumps and opening of Ca2+ membrane pumps; thus there will be influx of Ca2+ into the Beta-cells. In flux of Ca2+ then signals the the secretory organelles in the beta-cells to release insulin via exocytosis.
Personally i think it will be also interesting to see the direct effect of the test molecules on beta cell insulin secretion, independent of glucose (i.e. in the absence of glucose) in order to get a clearer picture about mechanism of action of the test molecules.
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