A SIMPLE METHOD TO PREDICT CELLULAR DENSITY IN ADIPOCYTE METABOLIC INCUBATIONS

OBJECTIVES: The density of isolated adipocyte suspensions, namely the cellular concentration, influences metabolic results when lipolysis an d the pattern of glucose metabolism are studied. It is often difficult to obtain reproducible adipocyte concentrations from experiment to ex periment, and investigators usually measure the cell concentration at the end rather than at the initiation of metabolic incubations. METHOD : A simple and rapid method to obtain reliable and predictable adipocy te concentration prior to metabolic incubations is described and valid ated. The method is based on determination of lipocrit, mean adipocyte diameter (by optical sizing), and calculation of volume, in aliquots of isolated adipocyte suspensions. MAIN OUTCOME MEASURES: Lipocrit, me an adipocyte volume, predicted and observed adipocyte number in isolat ed cell suspensions. RESULTS: In 15 experiments, adipocyte concentrati on was accurately predicted within 12-18% of actual concentration. Thi s is in contrast to the four-or five-fold differences usually encounte red in a series of experiments. CONCLUSION: One can rapidly predict th e number of adipocytes present in a given cell suspension with the pro posed method, and then correct it to a desired adipocyte concentration at the beginning of metabolic incubations. This method will help to e liminate the confounding effects of variable cell concentrations in in vitro metabolic experiments with isolated adipocytes.