Lactate production by white adipocytes in relation to insulin
sensitivity.
G., Faintrenie, and A. Glo`n.
URA D1341-CNRS, Laboratoire de Thermoregulation et Energetique de
l'Exercice, Lyon, France
APStracts 2:0372C, 1995.
Besides its lipogenic and lipolytic functions, adipose tissue has been
recognized as an important site of lactate production. We studied the
regulation of lactate production by epididymal adipocytes under
experimental conditions in which insulin sensitivity was increased
(cold-exposure) or reduced (glucose-perfusion). Insulin sensitivity
of adipocytes was assessed by its antilipolytic effect and its
stimulation of glucose uptake. We showed that in adipocytes isolated
from control and cold-exposed animals, glycerol and lactate
production rose simultaneously, in response to norepinephrine. On the
other hand, in adipocytes from glucose-perfused animals we observed a
dissociation between lipolytic and glycolytic responses. Indeed,
lactate production in response to norepinephrine reached 60 % of
maximal response (10-7 M) while the lipolytic response was still
basal. This phenomenon was the result of a desensitization of beta
-adrenergic receptors. However, the sensitivity of adipocytes to
stimulation of lactate production by catecholamines was not different
between control and glucose-perfused rats. Since lactate production
in response to norepinephrine was not affected by desensitization, it
suggests that lactate production is under alpha 1 adrenergic control.
We confirmed this hypothesis.
Received 21 June 1995; accepted in final form 6 October 1995.
APS Manuscript Number C361-5.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 November 95