[Islet perifusion: a new method to evaluate first-phase insulin secretory function of beta-cell in vitro].

Objective: To set up islet perifusion system, a new method to evaluate first-phase insulin secretory function of beta-cell in vitro.

Methods: Islet perifusion system was set up, including perifusion framework, waterbath system, infusion pump system, afferent system, islet capsule, and efferent system. Kinetics of insulin release in vitro was studied using the perifusion system. Pancreatic islets were isolated as mentioned above and used freshly after isolation. Size-matched 50 islets were placed in each column. Then the columns were gently closed with the top adaptors, immersed in vertical position and controlled temperature in the water bath at 37 degrees C. The perifusion medium was maintained at 37 degrees C in a water bath. And all columns were perifused in parallel at a flow rate of 0.5 ml/min with KRBB (2.8 mmol/L glucose) at 37 degrees C. After 60 min static incubation with KRBB (2.8 mmol/L glucose), the islets were stimulated in the continuous presence of a high concentration of 16.7 mmol/L glucose. Samples were collected every 20-second until 2 min, every 1 min until 5 min, thereafter every 5 min until 30 min. Samples were immediately stocked at -80 degrees C until further analysis. Insulin concentration was measured with an insulin RIA kit.

Results: An Islet perifusion system was established successfully, and kinetic curves of insulin secretion of db/m and db/db mice were traced out.

Conclusion: An established islet perifusion system, could be widely used to evaluate insulin secretory function of beta-cell in in vitro research of diabetes.