Obesity and endothelial dysfunction: mechanisms, method development and interventions

The principle aims of this thesis were to determine the effect of lowering plasma fatty acids (FA) on muscle microvascular blood volume (MBV) at rest and during exercise, investigate whether near-infrared spectroscopy (NIRS) can be used to measure muscle MBV in the obese, develop the contrast enhanced ultrasound (CEU) method in our laboratory for measuring muscle MBV of the human forearm, and use CEU to measure the MBV response to an oral glucose tolerance test (OGTT). No differences were observed in exercise-induced increases in MBV or resting MBV between control and low FA conditions created by niacin ingestion in lean and obese individuals. NIRS was not suited to measure muscle MBV in participants with a thick subcutaneous adipose tissue layer. The CEU method was successfully developed to measure MBV in the human forearm. CEU revealed a significant increase in MBV in response to an OGTT in lean trained individuals. This technique will be used in future studies to generate novel information on the suspected impaired MBV response after meal ingestion in obese individuals and to assess the effectiveness of interventions aimed at improving the MBV response and glycemic control to avoid the development of type II diabetes and cardiovascular disease