Regulation of Lipolysis in Small and Large Fat Cells of the Same Subject

Context: Large fat cell size is linked to type 2 diabetes risk and may involve an enhanced rate of adipocyte lipolysis causing elevated levels of fatty acids. Objective: Our objective was to study the role of fat cell size in the regulation of lipolysis within a subject. Design and Main Outcome Measures: Subcutaneous adipose tissue was obtained from 16 healthy subjects. Large and small adipocytes were isolated for each sample. Hormonal regulation of lipolysis and expression of lipolysis-regulating proteins were investigated. Results: No effect of cell size on the rate of lipolysis was observed when lipolysis was expressed per lipid weight of fat cells. However, when expressed per number of fat cells, the lipolysis was significantly higher in large as compared with small adipocytes. This was observed in both the unstimulated (basal) state and in the presence of the major lipolysis-regulating hormones such as catecholamines (stimulating), natriuretic peptides (stimulating), and insulin (inhibiting). The rec...