Integration of biochemical and physiologic effects of insulin on glucose metabolism

The major effects of insulin on tissues are: (1) Carbohydrate metabolism: ( a) It increases the rate of transport of glucose across the cell membrane i n adipose tissue and muscle, (b) it increases the rate of glycolysis in mus cle and adipose tissue, (c) it stimulates the rate of glycogen synthesis in a number of tissues, including adipose tissue, muscle, and Liver. It also decreases the rate of glycogen breakdown in muscle and liver, (d) it inhibi ts the rate of glycogenolysis and gluconeogenesis in the liver. (2) Lipid m etabolism: (a) It decreases the rate of lipolysis in adipose tissue and hen ce lowers the plasma fatty acid level, (b) it stimulates fatty acid and tri acylglycerol synthesis in tissues, although only to a minor extent in human s, (c) it increases the rate of very-low-density lipoprotein formation in t he Liver, (d) it increases the uptake of triglyceride from the blood into a dipose tissue and muscle, (e) it decreases the rate of fatty acid oxidation in muscle and liver, (f) it increases the rate of cholesterol synthesis in Liver. (3) Protein metabolism: (a) It increases the rate of transport of s ome amino acids into tissues, (b) it increases the rate of protein synthesi s in muscle, adipose tissue, liver, and other tissues, (c) it decreases the rate of protein degradation in muscle land perhaps other tissues, (d) it d ecreases the rate of urea formation. - These insulin effects serve to encou rage the synthesis of carbohydrate, fat and protein.