Procedure for determination of free and total cholesterol in micro- or nanogram amounts suitable for studies with cultured cells.

Procedures for the determination of free and total cholesterol in lipid extracts or sonicates of 10(4) cultured human skin fibroblasts are described. The method for free cholesterol employs cholesterol oxidase to generate H2O2 and peroxidase to catalyze the reaction of H2O2 with p-hydroxyphenylacetic acid to yield a stable fluorescent product. Cholesterol ester hydrolase is included for determination of total cholesterol. When samples of sonified cell suspensions are used directly, the extraction of lipids is avoided, permitting one person to carry out analyses of 30 or more subcultures in one day.