Selective antilipolytic effect of bacitracin in the isolated fat cell
Heckemeyer, C.; Solomon, S.S.; Barker, J.; Duckworth, W.C.
Biochemical and Biophysical Research Communications 108(1): 336-343
1982
ISSN/ISBN: 0006-291X PMID: 6293486 Document Number: 188513
Bacitracin, an antibiotic which decreases extracellular degradation, was used to study peptide hormone degradation in vitro. The biologic effectiveness of these hormones in the presence of bacitracin has received little attention. Inhibition of lipolysis induced by both epinephrine and glucagon was demonstrated in the isolated fat cell (IFC). IFC from epididymal tissue were incubated with 0.5 .mu.M epinephrine and increasing concentrations of bacitracin. Lipolysis was inhibited in a dose-dependent fashion, with a concentration of 5.7 .times. 10-4 M bacitracin suppressing lipolysis by 50%. Increasing the concentration of epinephrine in the presence of a constant dose of bacitracin overcame the antilipolytic effect. Bacitracin did not increase oxidation of glucose-U-C14 over basal. In the perfusion system, acute exposure to 5.7 .times. 10-4 M bacitracin plus 5 .times. 10-9 M glucagon suppressed lipolysis below unstimulated basal levels. Constant bacitracin perifusion produced no change in basal lipolysis but blunted the response to glucagon. 125I-Glucagon degradation was decreased in the presence of bacitracin. Additional studies with dibutyryl cAMP demonstrated that the antilipolytic effect of bacitracin is exerted at a step beyond the 2nd messenger. Bacitracin exerts a direct antilipolytic effect in isolated fat cells without stimulating glucose uptake and may afford a means of studying antilipolysis in the absence of other insulin-like effects.