AJP - Endocrinology and Metabolism, Vol 245, Issue 3 266-E272, Copyright © 1983 by American Physiological Society
Hormones modulate adipocyte membrane potential ATP and lipolysis via free fatty acids
M. L. Vallano, M. Y. Lee and M. Sonenberg
The hypothesis that lipolytic hormones reduce the mitochondrial electrical
potential in rat white adipocytes via free fatty acids (FFA) was examined.
Hormonal effects on plasma and mitochondrial membrane potentials were
evaluated with [3H]triphenylmethylphosphonium (TPMP+) and 86Rb+. FFA
generation was controlled by varying medium albumin concentrations. In 4.0%
albumin buffer, adrenocorticotropin or l-epinephrine increased
intracellular FFAs, produced cellular TPMP+ efflux, ATP depletion, release
of FFAs and glycerol, and no change in 86Rb+ distribution. In 0.5% albumin
buffer, greater intracellular FFA accumulation accompanied greater TPMP+
and ATP depletion, significant loss of cell-associated 86Rb+, and a
concomitant inhibition of FFA and glycerol release. Exogenous addition of
FFAs mimicked the effect of hormones on adipocyte TPMP+ distribution. TPMP+
and 86Rb+ uptake into adipocyte "ghosts" were unaffected by hormones. We
suggest that mitochondrial membrane depolarization is a metabolic response
to hormones via FFA accumulation by white adipocytes. The additional
hormonal effects that were observed in 0.5% albumin buffer may be related
to inhibition of lipolysis secondary to intracellular ATP depletion.
