Size, lipid and enzyme content of isolated human adipocytes in relation to nutritional state.

Abstract

The following parameters have been determined or calculated in isolated adipocytes from subcutaneous human adipose tissue from normal weight and obese subjects, obtained during surgical interventions or from volunteers who received local anaesthesia. Mean cell diameter, mean cellular lipid content, mean fat cell volume, and volume of lipid-free space. In fat cell extracts the activities of the following enzymes were measured: Glucose-6-phosphate-dehydrogenase, Phosphoglucomutase, Fructose-6-phosphatekinase, Hexosephosphate-isomerase, Aldolase, Glycerolaldehyde-phosphate-dehydrogenase, Phosphoglycerate-kinase, Pyruvate-kinase, Lactate-dehydrogenase. — In subjects with more than 50% overweight, the mean fat cell diameter was significantly increased. Mean fat cell volume calculated from fat cell diameter increased from 376±115 mm3 × 10−6 in normal weight to 799±99.5 mm3 × 10−6 in obesity. — In obese subjects the mean lipid content of individual adipocytes was twice as high as in normal weight subjects. The lipidfree residual space was also significantly larger in obesity. Nevertheless, this lipid-free space occupied a significantly smaller percentage of a defined fat cell mass in obese than in normal weight subjects. — Related to triglyceride content, the activities of HIM, G6PDH, and Aldolase were significantly reduced in adipocytes of subjects with more than 50% overweight, in a second series this was true for LDH also. There were significant negative correlations of the logarithms of these enzymes to the logarithm of overweight. There was an increased mean absolute enzyme content in adipocytes of obese subjects compared with those of normal weight persons. However, this increase was significant for LDH and HIM only. It is not certain that the enzyme pattern in the fat cells of obese subjects is related to the increase in cell volume. When related to a defined fat cell mass after correction for extra-cellular space, diminished activities for Aldolase, G6PDH, HIM, and LDH were found.