ASP stimulates glucose transport in cultured human adipocytes

Abstract

OBJECTIVE: The purpose of the present study was to examine the effect of Acylation Stimulating Protein (ASP) on glucose transport in cultured subcutaneous adipocytes. DESIGN AND SUBJECTS: Subcutaneous adipose tissue was obtained from non-obese, healthy females (18–32 y old) undergoing mammoplasty reduction. Preadipocytes were isolated and differentiated into adipocytes. MEASUREMENTS: Following the exposure of preadipocytes and adipocytes to ASP or insulin, glucose transport was assessed as [³H] 2-deoxy glucose uptake. The measurements were normalised per total cell protein. RESULTS: ASP increases specific membrane glucose transport in both preadipocytes and adipocytes in a time and concentration dependent manner. Stimulation in both cell types is rapid (within minutes), reaching a maximal effect between 1 and 4 h. However, after 24 h exposure to ASP, there is a downregulation in the response. The ASP response is greater following differentiation of preadipocytes to adipocytes and is compared to that of insulin. Dose response studies demonstrated a five-fold greater sensitivity of adipocytes (half-maximal concentration of ASP on adipocytes=0.5 µM, preadipocytes=2.3 µM). CONCLUSION: These results demonstrate that ASP not only stimulates triglyceride synthesis, but also glucose transport in differentiated human adipocytes and is consistent with a physiologically important role for ASP in postprandial energy storage.