Question

what stimulates insulin release: choose all that apply

a) activation of GLUT-2

b) deplorization of pancreatic beta cells triggered by high ATP

c) glucose inhibition of the mitochondria

d) inhibition of the hyperpolarization of the beta cells by K+

explain why you choose the options and why you do not choose the others

Answer 1

a) activation of GLUT-2

b) deplorization of pancreatic beta cells triggered by high ATP

d) inhibition of the hyperpolarization of the beta cells by K+

Explanation: Insulin release mechansim:

Glucose enters the β-cells through the glucose transporters, GLUT2. In  β-cell, it is phosphorylated to glucose-6-phosphate (G-6-P) by glucokinase.

- Glucose-6-phosphate enters glycolytic pathway.

- High-energy ATP molecules are produced by the oxidation of acetyl CoA (the Krebs cycle substrate), leading to a rise in the ATP:ADP ratio within the cell.

- High ATP:ADP ratio closes the ATP-sensitive potassium channel.

- This prevents potassium ions (K+) from leaving the cell by facilitated diffusion, leading to a buildup of intracellular potassium ions. As a result, the inside of the cell becomes less negative with respect to the outside, leading to the depolarization of the cell surface membrane.