The relation between insulin concentration and receptor number:

1. Increased insulin concentration decreases receptor number (down-regulation) and also decreases responsiveness to insulin i.e. resistance.

2. Decreased insulin concentration increases receptor number (up-regulation)and also increases responsiveness to insulin.

3. In obese (NIDDM) patients:

Overeating-hyperglycemia increases insulin secretion decreases number of insulin receptors insulin resistance.

Reduction of food intake diminishes hyperglycemia secretion increases receptors number and sensitivity. reduces insulin

Pharmacological actions of insulin:

1. Rapid transport effects:

Receptor stimulation sends signals to increase glucose transporter 4 vesicles on

cell membrane to increase glucose uptake by the cells

Insulin enhances cellular uptake of K. Ca & phosphate leading to decrease in their plasma levels.

2. Gradual (delayed) effects:

A- Carbohydrates: Insulin decreases blood glucose level through:

Increase cellular uptake and utilization of glucose.

Increase glycogen storage in the liver by enhancement of glycogenesis and inhibition of glycogenolysis.

Inhibition of gluconeogenesis.

B- Protein (anabolic):

Insulin increases cellular uptake of amino acids by skeletal musclesfor synthesis of protein