Glycogen Synthase

Publication Title: 
American Journal of Physiology. Endocrinology and Metabolism

Insulin-stimulated muscle glucose uptake is inversely associated with the muscle glycogen concentration. To investigate whether this association is a cause and effect relationship, we compared insulin-stimulated muscle glucose uptake in noncontracted and postcontracted muscle of GSL3-transgenic and wild-type mice. GSL3-transgenic mice overexpress a constitutively active form of glycogen synthase, which results in an abundant storage of muscle glycogen. Muscle contraction was elicited by in situ electrical stimulation of the sciatic nerve.

Author(s): 
Fogt, Donovan L.
Pan, Shujia
Lee, Sukho
Ding, Zhenping
Scrimgeour, Angus
Lawrence, John C.
Ivy, John L.
Publication Title: 
American Journal of Physiology. Endocrinology and Metabolism

Obstructive sleep apnea is characterized by intermittent obstruction of the upper airway, which leads to intermittent hypoxia. Myocardial glycogen is a major energy resource for heart during hypoxia. Previous studies have demonstrated that intermittent hypoxia rapidly degrades myocardial glycogen and activates glycogen synthase (GS). However, the underlying mechanisms remain undefined. Because sleep apnea/intermittent hypoxia usually happens at night, whether intermittent hypoxia leads to GS activation in the postabsorptive state is not known.

Author(s): 
Wu, Yangsong
Wang, Hong
Brautigan, David L.
Liu, Zhenqi
Publication Title: 
Metabolism: Clinical and Experimental

An alcoholic extract of Artemisia dracunculus L (PMI 5011) has been shown to decrease glucose and improve insulin levels in animal models, suggesting an ability to enhance insulin sensitivity. We sought to assess the cellular mechanism by which this botanical affects carbohydrate metabolism in primary human skeletal muscle culture.

Author(s): 
Wang, Zhong Q.
Ribnicky, David
Zhang, Xian H.
Raskin, Ilya
Yu, Yongmei
Cefalu, William T.
Publication Title: 
American Journal of Physiology. Endocrinology and Metabolism

Obstructive sleep apnea is characterized by intermittent obstruction of the upper airway, which leads to intermittent hypoxia. Myocardial glycogen is a major energy resource for heart during hypoxia. Previous studies have demonstrated that intermittent hypoxia rapidly degrades myocardial glycogen and activates glycogen synthase (GS). However, the underlying mechanisms remain undefined. Because sleep apnea/intermittent hypoxia usually happens at night, whether intermittent hypoxia leads to GS activation in the postabsorptive state is not known.

Author(s): 
Wu, Yangsong
Wang, Hong
Brautigan, David L.
Liu, Zhenqi
Publication Title: 
The Journal of Clinical Investigation

Hyperinsulinemia and increased visceral/abdominal fat (VF) are common features of human aging. To examine the relationships among VF, peripheral, and hepatic insulin sensitivity, we studied 4- and 18-mo-old male Sprague-Dawley rats (n = 42) fed ad libitum (4 AL and 18 AL) or moderately calorie restricted (18 CR) up to 18 mo of age. Total fat mass (FM) and VF were decreased in 18 CR to approximately one-third of that of 18 AL (P < 0.001), while lean body mass (LBM) was unchanged. Most important, 18 CR had more FM (65+/-6 vs. 45+/-6 g) but less VF (7.8+/-0.6 vs.

Author(s): 
Barzilai, N.
Banerjee, S.
Hawkins, M.
Chen, W.
Rossetti, L.
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