X. Fernandez et al., EFFECT OF EPINEPHRINE ADMINISTRATION ON GLYCOGEN-METABOLISM IN RED AND WHITE MUSCLE OF ANESTHETIZED PIGS (SUS SCROFA DOMESTICUS), Journal of the Science of Food and Agriculture, 68(2), 1995, pp. 231-239
The glycogenolytic effect of exogenous epinephrine was studied in whit
e (Longissimus) and red (Trapezius) muscle of anaesthetized pig. In ad
dition, we assessed the metabolic action of epinephrine during the 3 h
following the cessation of perfusion. Twelve purebred Large White pig
s, averaging 80 kg liveweight, were used. The animals were anaesthetiz
ed and perfused (0-15 min) with 5 mu g kg(-1) min(-1) epinephrine or s
aline (control animals). Blood samples were taken to determine plasma
levels of glucose, lactate and non-esterified fatty acids (NEFA). Musc
le samples were taken to determine the concentrations of glycogen and
related metabolites, and the activity ratio of the enzyme glycogen pho
sphorylase. Control animals showed stable levels of plasma and muscle
metabolites during the 3 h anaesthesia. However, the resting level of
the activity ratio of phosphorylase was high (80%). Epinephrine treatm
ent induced significant increases in plasma metabolites and an overall
significant glycogen depletion. The extent of epinephrine-induced gly
cogenolysis was greater in the red Trapezius than in the white Longiss
imus muscle. This was associated with a greater rise in the muscle lac
tate content and in the activity ratio of phosphorylase in the Trapezi
us muscle during epinephrine administration. In both muscles, no signi
ficant glycogen depletion was observed during 3 h following the cessat
ion of epinephrine administration. This occurred despite the fact that
the activity ratio of phosphorylase remained high in the Longissimus
muscle until the end of the experiment.