Insulin :glucagon ratio

High glucagon/insulin ratio causes elevated cAMP and increased levels of active protein kinase A. 

In summary, the data demonstrate that plasma glucose levels are maintained during an activity that greatly increases the use and oxidation of glucose stores within the body. The data also reveal that exercise is associated with an increase in the glucagon/insulin ratio and, a more subtle point, that plasma glucagon levels may fluctuate in a manner independent of insulin levels. 

The enzymes marked with the section symbol ( ) are regulated by covalent phosphorylation. In short, changes in the plasma glucagon/insulin ratio produce changes in the phosphate group content of these enzymes. Addition or removal of the phosphate group regulates the enzyme s activity, in accordance with the body s metabolic needs. 

The pathway of glucose breakdown is indicated in Figure 4.25 by heavy dots. Steps that are Inactivated by a rise in the glucagon/Insulin ratio are indicated by boldface Xs. As explained, PEPCK (more accurately, cytosolic PEPCK) activity is controlled by cellular levels of cAMP in the following manner. Cyclic AMP combines with a special protein (CREBP) to form a complex that binds to DN A. Where does the cAMP/CREBP complex bind The complex binds to a short stretch of... 

Lipoprotein lipase may be activated by changes in plasma glucagon and insulin. This activation appears to occur by an increase in migration of the enzyme to the capillary wall. For example, a decrease in the glucagon/insulin ratio, as with feeding, may provoke an increase in the proportion of enzyme located on the luminal wall and a decrease in the proportion that is intracellular. Feeding appears to provoke activation of the enzyme in adipose tissue, but not of the enzyme located in muscle or other hssues. 

A major factor in stinoulating ketone body production is increased availability of FTAs. An increased rate of FFA mobilisation from the adipose tissue, with the consequent increase in FFA levels in the liver, may be sufficient to enhance ketone body formation. Increased release of FFAs occurs when the glucagon/insulin ratio... 

The glucagon/insulin ratio can rise under certain pathological conditions (i.e., insulin-dependent diabetes). A small percentage of diabetics develop ketoacidosis, a condition that results from the overproduction and underuhlization of ketone bodies. Increased concentrations of p hydmxybutyrate and acetoacetate, which are acids, can cause a drop in the pH of the blood. This acidification, known as acidosis, can impair the ablLity of the heart to contract and result in a loss of consciousness and coma, which, in rare cases, may be fatal. Diabetic ketoacidosis may manifest as abdominal pain, nausea, and vomiting. A subject may hyperventilate (breathe quickly and deeply) to correct acidosis, as described under Sodium, Potassium, and Water in Chapter 10. It is the responsibility of the clinician, when confronted with a subject whose breath smells of acetone or who is hyperventilating, to facilitate prompt treatment. 

Glucagon-cAMP-kinase paOnvay, 162 Glucagon/insulin ratio, 161,182,183,... 

B) is at a maximum when the blood glucagon insulin ratio is high... 

Overactivity of gluconeogenesis due to increased secretion of catecholamines, cortisol, or growth hormone or an increase in the glucagon/insulin ratio (Chapter 22) leads to hyperglycemia and causes many metabolic problems. 

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