Glucose release

The phosphorylated glucose (G-6-P) occupies a key position in carbohydrate metabolism and can be utilized by 4 main pathways (a) by glucose release following enzymatic dephosphorylation (b) by... 

In solving problems of this type, you must realize that the oxidation of the glucose released energy in the form of heat and that some of the heat was absorbed by the water and the remainder by the calorimeter. You can use both the heat capacity of the calorimeter and the mass and specific heat of the water with the temperature change to calculate the heat absorbed by the calorimeter and water ... 

This value of 20 kJ/L O2 can be very useful for example, it can be used to calculate that a top-class marathon runner requires oxidation of 5 g of carbohydrate every minute during the race, provided that no other fuel is used. The athlete takes up 4 litres of oxygen each minute, which is equivalent to 4 x 20, or 80 kJ each minute as 1 g of glucose releases 16 kJ of energy, the glucose or glycogen used is 80/16 or 5 g each minute. 

Hypoglycaemia that arises when an increased rate of utilisation exceeds that of glucose release by the liver... 

The function of glucagon is to respond rapidly to an acute fall in the blood glucose level by stimulating glucose release by the liver and fatty acid release by adipose tissue. 

Studies using C -NMR spectroscopy show that, after 54 hours of starvation in normal lean subjects, gluconeogenesis accounts for 96% of glucose released from the liver (Rothman et at, 1991). 

All assays performed on digester samples were conducted in 100 mM Tris buffer pH 7.5 with substrate incubations at 37 C. Glucose-releasing assays used the same Tris buffer with 0.5% sodium azide added. Colorimetric products from enzyme assays were detected and recorded using a Milton-Roy model 601 spectrophotometer equipped with sipper and data printer. 

Analyses. Cellulase enzyme activities were determined as described earlier (21). Enzyme activities were expressed as international units (lU), i.e., mole glucose produced per minute. Cotton hydrolyzing activity was expressed as mg of glucose released in 24 hours per ml of enzyme. 

Metformin, a biguanide derivative, can lower excessive blood glucose levels, provided that insulin is present Metformin does not stimulate insulin release. Glucose release from the liver is decreased, while peripheral uptake is enhanced. The danger of hypoglycemia apparently is not increased. Frequent adverse effects include anorexia, nausea, and diarrhea Overproduction of lactic acid (lactate acidosis, lethality 50%) is a rare, potentially fatal reactioa Metformin is used in combination with sulfony-lureas or by itself. It is contraindicated in renal insufficiency and should therefore be avoided in elderly patients. 

The calcium-phosphoinositide and cAMP signaling pathways oppose one another in some cells and are complementary in others. For example, vasopressor agents that contract smooth muscle act by IP3-mediated mobilization of Ca2+, whereas agents that relax smooth muscle often act by elevation of cAMP. In contrast, cAMP and phosphoinositide second messengers act together to stimulate glucose release from the liver. 

In the first few hours after a meal, the blood glucose level is diminished slightly, and tissues receive glucose released from liver glycogen. There is little or no synthesis of lipids. By 24 hours after a meal, blood glucose has fallen further, insulin secretion has slowed, and glucagon secretion has increased. These hormonal signals... 

Recent studies indicate that the various phosphohydrolase and phosphotransferase activities of glucose-6-phosphatase are affected by numerous metabolites (see Table X and Sections II,C and III,D,4). The possible significance of observed activation or inhibition by a number of these compounds in vitro relative to regulation of both types of activity of the enzyme in vivo has been considered in a number of instances. Possible modes of control of net glucose release, involving the regulation by a variety of factors, of both hydrolytic and synthetic activities of the enzyme, have been discussed in considerable detail in earlier reviews by the author (9, 10). 

Figure 1. Natural antibodies in normal human and rabbit sera against liposomes containing no glycolipid, galactosylceramide, or lactosylceramide. Glucose release measured from liposomes containing DMPC, CHOL, DCP, and, where indicated, galactosylceramide (150 fig/nmol PC) or lactosylceramide (150 ng/fimol PC).

Figure 4. Reactivity of purified immune anti-CDH antibodies against CMH-con-taining liposomes. Glucose release measured from liposomes containing DPPC, CHOL, DCP, and the amounts of CMH shown (6).

OF TRAPPED GLUCOSE RELEASED FROM LIPOSOMES CONTAINING ... 

---