Studies of a child with glycogenosis revealed an increased concentration of glycogen and low phosphorylase activity in her liver. Using mixtures of homogenates of the patient's liver and of normal liver, we found the low phosphorylase activity to be caused by a deficiency of phosphorylase kinase and not of hepatic phosphorylase. The fact that phosphorylase activity was restored to normal values...

The interplay between hepatic glycogen metabolism and blood glucose levels is a paradigm of the rhythmic nature of metabolic homeostasis. Here we show that mice lacking a functional PER2 protein (Per2 (Brdm1) ) display reduced fasting glycemia, altered rhythms of hepatic glycogen accumulation, and altered rhythms of food intake. Per2 (Brdm1) mice show reduced hepatic glycogen content and altere...

The activation of glycogen phosphorylase by epinephrine was examined in hepatocytes from fed female rats administered 0.25 mg of triiodothyronine per kg of body weight daily for 2 days. Basal cyclic AMP accumulation by the hepatocytes was not altered by the thyroid hormone administration. Basal glycogen phosphorylase a activities were 1.18 f 0.07 units/mg of protein in control and 0.37 -+ 0.04 ...

The function of insulin as a regulator of permeability of cell membranes is, at present, in the foreground of attention. Nevertheless, experiments such as those reported in the lucid paper by Kipnis and Corin on the change of the temperature coefficient for pentose transfer into diaphragm with insulin addition indicate a possible shift from diffusion to a chemical and therefore probably enzymat...

BACKGROUND Ischemic stroke is the combinatorial effect of many pathological processes including the loss of energy supplies, excessive intracellular calcium accumulation, oxidative stress, and inflammatory responses. The brain's ability to maintain energy demand through this process involves metabolism of glycogen, which is critical for release of stored glucose. However, regulation of glycogen...

A purified commercial preparation of Escherichia coli alkaline phosphatase (EC 3.1.3.1) has been shown to dephosphorylate several phosphoproteins including bovine heart glycogen synthase D, mixed phosphohistones, and rabbit skeletal muscle phosphorylase kinase but not rabbit skeletal muscle glycogen phosphorylase. Alkaline phosphatase completely removed phosphate groups previously added during ...

The influence of differences in glycogen concentration on glycogen breakdown and on phosphorylase activity was investigated in perfused contracting rat skeletal muscle. The rats were preconditioned by a combination of swimming exercise and diet (carbohydrate-free or carbohydrate-rich) in order to obtain four sub-groups of rats with varying resting muscle glycogen concentrations (range 10-60 mum...

In 1968, Kugelberg and Edstr6m described a histochemical method to localize skeletal muscle fibres belonging to a single motor unit by depletion of their glycogen. The authors concluded that "contractions produced striking changes in the phosphorylase activity and glycogen content, which varied in different types of fibres". Thus, the pattern of histochemically demonstrated activity of phosphor...

McArdle has reported a "myopathy due to a defect in muscle glycogen breakdown"' which appears to be a type of glycogen storage disease distinct from the previously reported classes.2 Schmid and Mahler' using muscle homogenates from a patient similar to the one described by McArdle have found that lactate is formed from added glucose 1-phosphate at a rate comparable to that of controls, but addi...

Over 95% of the pyridoxal phosphate (PLP) in skeletal is bound to one protein, glycogen phosphorylase. This, and the fact that phosphorylase constitutes approx. 5% of the soluble protein in skeletal muscle, introduce the possibility that PLP might be used as a specific label to identify degradation intermediates of the enzyme. In this investigation, we have developed immunological methods, usin...