RASOULI M, SHARIF M, ZAHRAIE M. EPINEPHRINE SUPPRESSES SECRE TION ORVLDLASSOCIATED TRIACYLGLYCEROLAND INCREASES TRIACYLGLYCEROL AND PHOSPHOL IPID CON TEN TS IN ISOL ATED RAT HEPATOCY TES. Med J Islam Repub Iran 2000; 14 (1) :61-68
URL:
http://mjiri.iums.ac.ir/article-1-902-en.html
From the Department of Biochemistry, Faculty of Medicine, Tehran University of Medical Sciences, Tehran , MehdIRasoull@hotmall.Com
Abstract: (4490 Views)
The effect of epinephrine on triacylglycerol secretion was investigated in
isolated rat hepatocytes. The effect appeared at concentrations of more than 1 µM
and reached a plateau at 10 µM. Epinephrine concentration for half of the maximal
bioeffect (EC50) was about 1 µM. Epineplrrine at a concentration of 10 µM suppressed
triacylglycerol secretion by 33% and increased its cellular content by approximately
18%. The total triacylglycerol content of the system (sum of the cell and the
incubation medium) was constant at all concentrations of epinephrine. Time
course experiments for triacylglycerol secretion exhibited relatively similar results
on the basis of lipid analysis with or without lipid extractions. On the former basis
triacylglycerol secretion versus time followed a linear relationship with a slope of
1.47 ± 0.11 µmole TG/3h/ g wet liver. Time course curves of cellular lipids revealed
that cellular triacylglycerol and phospholipid contents in the presence of epinephrine
were higher than the control at all time points, and the difference was constant
during time. Furthermore, in the presence of glucose (20 mM) and oleate (0.25
mM), intracellular triacylglycerol content increased markedly (≥45%) whereas
cellular phospholipid content remained constant. It is proposed that epinephrine
exerts an inhibitory effect on VLDL secretion probably through blocking in the
secretory pathway.