Glucose Transporter 4 Expression in White Blood Cells of Young and Old Sled Dogs

Abstract

Obesity has reached alarming levels in the United States Recent statistics show that 1 out of 3 individuals are either obese or overweight! The principle role of the hormone insulin is to mediate the redistribution of the glucose transporter- 4 (Glut4) from an intracellular vesicle pool into plasma membranes of insulin-responsive tissues and thus regulating the uptake of glucose. Insulin resistance is characterized by an inability of cells to respond to insulin upon stimulation with glucose and presents as an important risk factor for the development of type 2 diabetes. Glut4 is the only glucose transporter responsive to insulin and is thought to be found exclusively in muscle an adipose cells. But recently, Maratou et al (2007) demonstrated that there is Glut4 in white blood cells (WBC)collected from human subjects in response to insulin activation. Dogs have been used as a proven biomedical research model for diabetes for over a century since dogs develop insulin dependent and independent forms of diabetes similar to humans. Sled dogs are incredible athletes that provide a homogenous population for studying environmental impacts such as nutrition and exercise on blood parameters. The goal of this study was to 1) develop a protocol to measure Glut4 in white blood cells of sled dogs and 2) compare Glut4 levels in young versus old sled dogs assuming that old sled dogs are at higher risk of diabetes.