Which factor stimulates insulin release?

Insulin release is primarily stimulated by glucose, which is the main regulator of insulin secretion from the beta cells of the pancreas. When glucose levels rise, such as after eating, it is detected by the pancreatic beta cells. The metabolism of glucose leads to an increase in ATP production, which ultimately causes depolarization of the cell membrane and opening of voltage-dependent calcium channels. The influx of calcium then triggers the exocytosis of insulin granules into the bloodstream.

Additionally, certain amino acids, particularly arginine and alanine, can enhance insulin release. These amino acids can increase the intracellular availability of ATP similarly to glucose, further promoting insulin secretion. This is why the correct choice includes both glucose and amino acids, specifically alanine, as they collectively play a crucial role in stimulating the release of insulin.

Other factors mentioned, such as fatty acids, glucagon, and cortisol, have different roles in the regulation of glucose metabolism and insulin balance but do not directly stimulate insulin release like glucose and amino acids do. For instance, fatty acids can influence insulin sensitivity rather than being direct stimulators of its release, glucagon is actually more involved in increasing blood glucose levels rather than promoting insulin secretion, and cortisol has a role in glucose homeostasis and stress response