Stimulation of glucose utilization and inhibition of lipolysis by polyene antibiotics in isolated adipose cells

Abstract

Polyene antibiotics, such as filipin, pimaricin, and nystatin, like insulin, were found to stimulate the uptake and the metabolism of extracellular glucose by isolated adipose cells. Such stimulation, however, was abolished when the polyenes were present at high concentrations. The filipin-stimulated lipogenesis from glucose was inhibited by phlorizin, 3- O-methylglucose, 2-deoxyglucose and puromycin. Polyenes neither enhanced nor inhibited the insulin- or the protease-stimulated glucose utilization, but inhibited the deoxyfrenolicin-stimulated process to variable degrees. No significant addition to the stimulatory effects of glucose utilization was observed in the copresence of phospholipase C and polyenes. Phospholipase C, at concentrations high enough to abolish its own stimulation of glucose utilization, also abolished the stimulatory effects of filipin or nystatin, but not of pimaricin. Like insulin, polyenes stimulated still further the lipogenesis from glucose in the presence of palmitic acid. Polyenes blocked lipolysis mediated by either norepinephrine, corticotropin, caffeine or theophylline. It is suggested that the interactions of polyenes with the phospholipid-cholesterol constituent of the lipoprotein membrane imparted to adipose cells activities characteristic of those of the insulin-treated cells.