Niewoehner, Catherine B., M.D.

ENDOCRINOLOGY AND METABOLISM/INTERNAL MEDICINE

Laboratory Research is focused upon the effects of dietary carbohydrate on liver glycogen metabolism, since maintenance of normal glucose tolerance and energy reserves depend upon rapid uptake and metabolism of sugars and storage as glycogen. Effects of oral loads of glucose, fructose, sucrose, galactose, lactose, lactate and glutamine on liver metabolism are being examined in fasted, fed and diabetic rat models. We wish to determine: • Whether under any conditions of feeding or fasting gluconeogenesis continues to be active, albeit at a modified rate, thus sparing ingested glucose for metabolism by glucose-requiring tissues. • What are the mechanisms by which glycogen synthesis and glycogenolysis are regulated during the transition from the fed to the fasted state? • What are the effects of oral monosaccharide loads on hepatic oxygen consumption versus glycogen synthesis? • What is the mechanism by which lactate and glutamine activate glycogen synthesis in the absence of increased conversion of glycogen synthase to its active forms? • Is there a role for lactate and glutamine in the regulation of glucose phosphatase and hepatic glucose production?