Membrane depolarization, cyclic AMP, and glycerol release by brown adipose tissue.

WILLIAMS, JOHN A., AND E. K. MATTHEWS. Membrane depolarization, cyclic AMP, and glycerol release by brown adipose tissue. Am. J. Physiol. 227(4) : 987-992. 1974.-The possible relationships between membrane depolarization, cyclic AMP and glycerol release were studied in brown adipose tissue obtained from young rats. Noradrenaline, theophylline, and dibutyryl cyclic AMP, at concentrations which stimulated glycerol release, all depolarized the cells by 15-25 mV. Depolarization by an elevated concentration of K+ in the medium or removal of Na+ or Clfailed to influence glycerol release. Noradrenaline acted to increase tissue levels of cyclic AMP with the effect potentiated by theophylline. Fatty acids and other uncouplers of oxidative phosphorylation also depolarized the fat cell comparably to noradrenaline. Thus, membrane depolarization is not an adequate stimulus for lipolysis, and part of the depolarization may, in fact, be mediated through the action of cyclic AMP on lipolysis.