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Physiology

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Endocrinology

Question
8 out of 10
 

Glucose increases plasma insulin by a process that involves: (LQ)



A GLUT1
B GLUT2

C GLUT3
D SGLT1

Ans. B GLUT2

Mechanism of Insulin secretion by Beta cells :- .

I. Glucose is the key regulator of insulin secretion by pancreatic Beta cells, others are – amino acids, ketones, various nutrients, GIP, and neurotransmitters.

II. Glucose stimulation of insulin secretion begins with its transport into beta cells by the GLUT-2 glucose transporter.

III. Glucose phosphorylation by glucokinase is the rate-limiting step that controls glucose regulated insulin secretion.

4. ATP sensitive K+ Channel

a. Consists of two proteins

i. SUR (Sulphonyl Urea Receptor) and

ii. Inwardly rectifying K+ channels.

b. Insulin secretagogues :

Sulphonyl Urea and Non Sulphonyl Urea

(Repaglinide, Nateglinide) increase insulin secretion by binding with SUR of ATP sensitive -K+ channel inhibit it reducing conductance of the K+-channel depolarization influx of Ca++→↑ insulin secretion Insulin stimulates glucose uptake through GLUT-4 transporter in the skeletal muscle, cardiac muscle and adipose tissues.

i. SGLT-1 transporter

1) Sodium dependent unidirectional transporter

2) Secondary active transport .

3) Present in small intestine and kidney

4) Mediates active uptake of glucose from the lumen of the intestine and reabsorption of glucose in PCT of kidney against a conc. gradient.

ii. GLUT-I-transporter (fascilitated diffusion) :

1) Mediates basal uptake of glucose (independent of insulin) in the Placenta, BBB, Brain, RBC, Kidney, Colon, many other organs.