Hormonal regulation of hepatic soluble phosphatidate phosphohydrolase

Lehtonen, Mervi A.; Savolainen, Markku J.; Hassinen, Ilmo E.

doi:10.1016/0014-5793(79)80270-7

Cited by 60 publications

(22 citation statements)

References 28 publications

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“…Here, there was no significant difference in the concentrations of dexamethasone needed to stimulate these two activities. The increases in phosphatidate phosphohydrolase compare reasonably well with the 2.74-fold stimulation obtained in [4] by perfusing isolated livers with cortisol. In vivo, the phosphohydrolase activity has been observed to increase by 2-7-fold when the circulating levels of corticosterone increase from -0.1 PM to l-3 yM [16-191. In other experiments we replaced the foetal calf serum in the medium used for hepatocyte incubations by 20 mg fatty acid-poor bovine serum albumin/ml.…”

supporting

confidence: 77%

“…3.4) and this enzyme appears to facilitate an increased rate of triacylglycerol synthesis in a variety of physiological conditions [3-61. Direct evidence for the involvement of cortisol in stimulating the phosphohydrolase activity has been demonstrated with isolated perfused liver [4], but not with isolated hepatocytes. This work involves the latter system which can be more readily employed to investigate how a variety of hormones interact to control hepatic glycerolipid synthesis.…”

Section: Introductionmentioning

confidence: 99%

“…Actinomycin D also prevented the increases in activity that were observed in vitro after perfusing livers with cortisol [4], and those seen in vivo after subtotal hepatectomy [20].…”

mentioning

confidence: 99%

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Stimulation of the activities of phosphatidate phosphohydrolase and tyrosine aminotransferase in rat hepatocytes by glucocorticoids

Jennings¹,

Lawson²,

Fears³

et al. 1981

FEBS Letters

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supporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

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Stimulation of the activities of phosphatidate phosphohydrolase and tyrosine aminotransferase in rat hepatocytes by glucocorticoids

Jennings¹,

Lawson²,

Fears³

et al. 1981

FEBS Letters

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“…180 perfused with cortisol (Lehtonen et al, 1979). Adrenalectomy of rats abolishes over 85% of the ethanol-induced increase in phosphohydrolase activity (Brindley et al, 1979a).…”

mentioning

confidence: 99%

Control of hepatic triacylglycerol synthesis. Diurnal variations in hepatic phosphatidate phosphohydrolase activity and in the concentrations of circulating insulin and corticosterone in rats

Knox¹,

Sturton²,

Cooling³

et al. 1979

Biochemical Journal

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Male rats were kept for 14 days with alternating 12h periods of light and darkness. The hepatic activity of soluble phosphatidate phosphohydrolase and the concentration of serum insulin were maximum at about 2h after dark. The peak concentration of serum corticosterone occurred 2h before the dark period. It is proposed that corticosterone is partly responsible for the increased phosphohydrolase activity, and that this enables the liver to increase its capacity to synthesize triacylglycerols during the period of maximum feeding.

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“…This enzyme has been shown to be increased in diabetes^2 8 ], after cortisol application and ethanol feeding! 29 1, as well as carbohydrate refeeding^ conditions, all of which exhibit increased rates of liver triacylglycerol synthesis in vitro. The fact, however, that this enzyme is increased in hyperinsulinemic (carbohydrate-refeeding) and hypoinsulinemic (diabetes mellitus) states, sheds some doubt on the unique role of phosphatidate phosphohydrolase.…”

Section: The Effect Of Substrates and Ethanolmentioning

confidence: 98%

Regulation of Net Triacylglycerol Synthesis by Metabolic Substrates in Isolated Rat Liver Cells

Wirthensohn¹,

Brocks²,

Guder³

1980

Hoppe-Seyler´s Zeitschrift für physiologische Chemie

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Triacylglycerol metabolism was studied in isolated rat hepatocytes using a fully enzymatic method to measure cellular glyceride-glycerol. With this method 40 and 50 μτηοΐ triacylglycerol were found per g cellular protein in liver cells from fed and starved rats, respectively, comparable to values obtained after organic solvent extraction and alkaline hydrolysis of neutral lipids. Carbohydrate refeeding of animals increased triacylglycerol levels in hepatocytes to 80 μπιοΐ. Upon incubation without fatty acids a 15 % decrease in cellular triacylglycerol was found in 60 min. When ImM oleate or palmitate were added cellular triacylglycerol increased.. The rates of net triacylglycerol synthesis were not significantly different with oleate and palmitate. Starvation reduced the rates from both fatty acids, whereas carbohydrate refeeding led to a marked increase in net triacylglycerol synthesis. Besides 20mM glucose, 5mM L-lactate and 5mM fructose stimulated triacylglycerol synthesis from fatty acids. The stimulatory effect of lactate was higher in hepatocytes from starved animals, so that the differences in triacylglycerol synthesis between liver cells from fed and starved rats were abolished. Fatty acids taken up and not recovered in newly formed triacylglycerol were released as ketone bodies.When radioactive lactate was offered to cells from starved rats, label incorporated into neutral lipids was exclusively recovered from the glycerol moiety of triacylglycerols. 5mM ethanol which alone increased fatty acid esterification, reduced the stimulatory effect of lactate but increased the effect of fructose on net triacylglycerol formation.These findings indicate that esterification rate in liver cells from starved rats can be limited by availability of α-glycerophosphate, which is provided by glyceroneogenesis. The possible physiological significance of these findings is discussed with regard to liver cell heterogeneity and nutritional adaptation of liver triacylglycerol formation. Regulation der Triacylglycerinsynthese in Hepatozyten durch metabolische SubstrateZusammenfassung: Mit einer vollenzymatischen Methode zur Bestimmung von zellul rem Glyceridglycerin wurde der Triacylglycerinstoffwechsel isolierter Hepatozyten der Ratte untersucht. Der Triglyceridgehalt in Leberzellen von gef tterten und hungernden Tieren lag mit dieser Methode bei 40 bzw. 50 μιηοΐ/g Protein. Vergleichbare Werte wurden nach Extraktion mit organischen L sungsmitteln und alkalischer Hydrolyse der Neutrallipide gefunden. Kohlenhydratwieder-

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Hormonal regulation of hepatic soluble phosphatidate phosphohydrolase

Cited by 60 publications

References 28 publications

Stimulation of the activities of phosphatidate phosphohydrolase and tyrosine aminotransferase in rat hepatocytes by glucocorticoids

Stimulation of the activities of phosphatidate phosphohydrolase and tyrosine aminotransferase in rat hepatocytes by glucocorticoids

Control of hepatic triacylglycerol synthesis. Diurnal variations in hepatic phosphatidate phosphohydrolase activity and in the concentrations of circulating insulin and corticosterone in rats

Regulation of Net Triacylglycerol Synthesis by Metabolic Substrates in Isolated Rat Liver Cells

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