Human fat cell adenylate cyclase: regional differences in adrenaline responsiveness

The effect of adrenaline on adenylate cyclase activity in membranes prepared from human abdominal and gluteal adipose tissue was examined. Basal enzyme activity averaged 1.0 mmol cAMP/mg protein/15 min in abdominal tissue and 0.68 nmol cAMP/mg protein/15 min in ghosts from the buttock. Maximally effective concentrations of sodium fluoride (20 mmol/1) induced an eight-fold increase in both membrane preparations. The maximal response to adrenaline (1.0 mmol/1) averaged 170% in ghosts of abdominal tissue compared with 60% in gluteal membranes. The concentrations of adrenaline required to produce half-maximal stimulation were similar in membrane preparations of both regions (about 5 X 10(-5) mol/1).