TITLE:
Responses of the perfused liver of neonatal type 2 diabetic rats to gluconeogenic and ammoniogenic substrates
AUTHORS:
Mirian Carvalho-Martini, Fumie Suzuki-Kemmelmeier, Denise Silva de Oliveira, Jurandir Fernando Comar, Adelar Bracht
KEYWORDS:
Type 2 Diabetes; Gluconeogenesis; Ammoniogenesis; Alanine; Lactate
JOURNAL NAME:
Health,
Vol.2 No.5,
May
27,
2010
ABSTRACT: The responses of livers from rats with type 2 diabetes to alanine (gluconeogenesis and ammonia detoxification) and other gluconeogenic substrates were investigated. The experimental system was the isolated perfused rat liver. Neonatal type 2 diabetes was induced with streptozotocin. Ammoniogenesis from endogenous substrates was 610% higher in livers from diabetic rats when compared to the control condition. Alanine (2.5 mM) ammoniogenesis was 285% higher in livers of diabetic rats. Gluconeogenesis from the following substrates was smaller in the liver of diabetic rats: Alanine (?43.5%), lactate (?28.3%) and glycerol (?30.5%). Pyruvate gluconeogenesis was normal. The high rate of ammoniogenesis explains the moderate hyperammonemia of type 2 diabetic rats. The enzymatic machinery of the gluconeogenic pathway of type 2 diabetic rats seems to be adapted to low rates of glucose removal by extrahepatic tissues. A significant contribution of gluconeogenesis to the fasting hyperglycemia can be expected only by short-term up-regulation mechanisms.