This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Pharmacology
[{'content': 'Effect of Potassium ionophore valinomycin on beta cells of pancreas is? \nSelect and explain. \nA. Decrease the secretion of insulin, B. Insulin secretion increases, C. C-peptide secretion increases, D. Increase secretion of both insulin and C- peptide', 'role': 'user'}, {'content': 'Answer: A \nExplanation: (a) Decrease the secretion of insulinRef: style="font-size: 1.04761904761905em; font-family: Times New Roman, Times, serif"> and http://www. eje-online. org/content/88/1/113Valinomycin interferes with the insulin releasing effect of glucose by increasing the potassium permeability of the B cell membrane.About ValinomycinIt is a member of the group of natural neutral ionophores because it does not have a residual charge. It is highly selective for potassium ions within the cell membrane and functions as a potassium-specific transporter. It facilitates the movement of potassium ions through lipid membranes "down" the electrochemical potential gradient. A very little literature is available regarding valinomycin.Theoretically, hyperpolarization of beta cells due to increased K+ permeability caused by valinomycin may lead to inhibition of insulin release (depolarization is needed for insulin release from beta cells).', 'role': 'assistant'}]