Regulation of acyl CoA: Cholesterol acyl transferase (ACAT) activity by mevalonate and cholesterol in isolated rat hepatocytes during perinatal development

1986 ◽  
Vol 6 (8) ◽  
pp. 735-740
Author(s):  
G. Bruscalupi ◽  
L. Conti Devirgiliis ◽  
S. Leoni ◽  
F. Piemonte ◽  
A. Trentalance
Keyword(s):  
Developmental Stages ◽  
Rat Hepatocytes ◽  
Differential Sensitivity ◽  
Substrate Effect ◽  
Acyl Transferase ◽  
Cholesterol Acyl Transferase ◽  
Isolated Rat Hepatocytes ◽  
Acat Activity ◽  
Stimulation Of

Acyl CoA: cholesterol acyl transferase (ACAT) activity presents marked oscillations and differential sensitivity to the “in vitro” stimulation of the kinase-phosphatase modulatory system in the perinatal rat liver. The regulation of this enzyme activity by some modulators generally active in adulthood, such as cholesterol, lipoproteins and mevalonate, has been studied in hepatocytes isolated at different developmental stages. A lack of effect of mevalonate and a positive effort of lipoprotein cholesterol have been observed at the fetal and neonatal stages. A differential prevalence is suggested of one of the two modulatory mechanisms (phosphorylation-dephosphorylation system, or substrate effect) at each developmental stage.

Short term regulation of acyl CoA: Cholesterol acyl transferase (ACAT) activity in the regenerating and perinatal liver

1985 ◽  
Vol 5 (3) ◽  
pp. 237-242 ◽  
Author(s):  
G. Bruscalupi ◽  
S. Leoni ◽  
M. T. Mangiantini ◽  
F. Piemonte ◽  
S. Spagnuolo ◽  
...  
Keyword(s):  
Differential Sensitivity ◽  
Liver Development ◽  
Acyl Transferase ◽  
Regenerating Liver ◽  
Hepatic Cholesterol ◽  
Short Term ◽  
Cholesterol Acyl Transferase ◽  
Acat Activity ◽  
Stimulation Of

Acyl coenzyme A:cholesterol acyltransferase (ACAT), the enzyme catalyzing the hepatic cholesterol esterification could be involved in the modified availability of cholesterol detectable in proliferating systems. While no significant variations are detectable in the regenerating liver, the modified ACAT activity during liver development and its differential sensitivity to the in vitro stimulation of modulatory systems suggest an involvement of the enzyme in this proliferating process.

scholarly journals Stimulation of [1-14C]oleate oxidation to 14CO2 in isolated rat hepatocytes by the catecholamines, vasopressin and angiotensin. A possible mechanism of action

1983 ◽  
Vol 212 (1) ◽  
pp. 85-91 ◽  
Author(s):  
M C Sugden ◽  
D I Watts
Keyword(s):  
Phosphoenolpyruvate Carboxykinase ◽  
Tricarboxylic Acid Cycle ◽  
Rat Hepatocytes ◽  
Tricarboxylic Acid ◽  
Isolated Rat Hepatocytes ◽  
Acid Cycle ◽  
14Co2 Production ◽  
Oxoglutarate Dehydrogenase ◽  
Stimulation Of

Adrenaline, noradrenaline, vasopressin and angiotensin increased 14CO2 production from [1-14C]oleate by hepatocytes from fed rats but not by hepatocytes from starved rats. The hormones did not increase 14CO2 production when hepatocytes from fed rats were depleted of glycogen in vitro. Increased 14CO2 production from]1-14C]oleate in response to the hormones was observed when hepatocytes from starved rats were incubated with 3-mercaptopicolinate, an inhibitor of phosphoenolpyruvate carboxykinase. 3-Mercaptopicolinate inhibited uptake and esterification of [1-14C]oleate, slightly increased 14CO2 production from [1-14C]oleate and greatly increased the [3-hydroxybutyrate]/[acetoacetate] ratio. In the presence of 3-mercaptopicolinate 14CO2 production in response to the catecholamines was blocked by the α-antagonist phentolamine and required extracellular Ca2+. The effects of vasopressin and angiotensin were also Ca2+-dependent. The actions of the hormones of 14CO2 production from [I-14C]oleate by hepatocytes from starved rats in the presence of 3-mercaptopicolinate thus have the characteristics of the response to the hormones found with hepatocytes from fed rats incubated without 3-mercaptopicolinate. The stimulatory effects of the hormones on 14CO2 production from [1-14C]oleate were not the result of decreased esterification (as the hormones increased esterification) or increased β-oxidation. It is suggested that the effect of the hormones to increase 14CO2 production from [1-14C]oleate are mediated by CA2+-activation of NAD+-linked isocitrate dehydrogenase, the 2-oxoglutarate dehydrogenase complex, and/or electron transport. The results also demonstrate that when the supply of oxaloacetate is limited it is utilized for gluconeogenesis rather than to maintain tricarboxylic acid-cycle flux.

scholarly journals Differential sensitivity of insulin- and adaptive-regulation-induced system A activation to microtubular function in skeletal muscle

1992 ◽  
Vol 281 (2) ◽  
pp. 407-411 ◽  
Author(s):  
A Gumà ◽  
A Castelló ◽  
X Testar ◽  
M Palacín ◽  
A Zorzano
Keyword(s):  
Skeletal Muscle ◽  
Rat Hepatocytes ◽  
Cytochalasin D ◽  
Differential Sensitivity ◽  
Dependent Manner ◽  
Isolated Rat Hepatocytes ◽  
Prolonged Incubation ◽  
Adaptive Regulation ◽  
System A ◽  
Stimulation Of

1. Insulin and adaptive regulation are known to stimulate system A amino acid transport activity in skeletal muscle. The present study was designed to investigate whether activation of system A in muscle is a consequence of processes which rely on microtubule or microfilament function. To that end, extensor digitorum longus (EDL) muscles were incubated in the presence of colchicine and cytochalasin D, well-known inhibitors of microtubule and microfilament activity respectively. 2. Basal alpha-(methyl)aminoisobutyric acid (MeAIB) uptake decreased after incubation with 5 microM-colchicine in a time-dependent manner. In keeping with this, adaptive regulation of MeAIB uptake caused by prolonged incubation in the absence of amino acids was substantially decreased in the presence of colchicine. 3. Under these conditions, stimulation of MeAIB uptake by insulin was unaltered in muscle in the presence of colchicine. This contrasted with the insulin-induced stimulation of MeAIB uptake by isolated rat hepatocytes, which was markedly decreased by colchicine. 4. Cytochalasin D, an agent that disrupts microfilaments, did not inhibit basal or insulin-stimulated MeAIB uptake by the incubated muscle. 5. Neither colchicine nor cytochalasin D modified the stimulatory effect of insulin on 3-O-methylglucose uptake by EDL muscle. 6. We conclude that up-regulation of system A by synthesis of new carriers depends on the integrity of microtubular function both in skeletal muscle and in hepatocytes. Microtubules might play a role in the movement of system A-containing vesicles from the Golgi network to the plasma membrane.

The Hep G2 Cell Line as a Possible Alternative to Isolated Hepatocytes in Cytotoxicity Studies

1988 ◽  
Vol 16 (1) ◽  
pp. 16-22
Author(s):  
Marina Marinovich ◽  
Jose L. Lorenzo ◽  
Liliana M. Flaminio ◽  
Agnese Granata ◽  
Corrado L. Galli
Keyword(s):  
Cell Line ◽  
Rat Hepatocytes ◽  
Prostaglandin E ◽  
Human Hepatoma ◽  
Hep G2 ◽  
Hep G2 Cells ◽  
Isolated Rat Hepatocytes ◽  
G2 Cells ◽  
Isolated Rat

The hepatotoxicity of carbon tetrachloride (CC14) was evaluated in vitro in freshly isolated rat hepatocytes and in the human hepatoma cell line, Hep G2. Toxicity was assessed by the leakage of cytosolic enzymes (lactate dehydrogenase and aspartate aminotransferase) and cell viability (trypan blue exclusion). The established human cells were less sensitive to CCl4-induced injury; higher doses of the toxic agent and longer incubation times were necessary to elicit cell damage. Micromolar concentrations of prostaglandin E2 significantly decreased enzyme leakage in both Hep G2 cells and rat hepatocytes challenged with CC14; a stable derivative of prostacyclin (ZK 36374) was ineffective. These results suggest that human hepatoma Hep G2 cells may represent a valid alternative to isolated rat hepatocytes for an initial approach to the in vitro evaluation of cell toxicity.

scholarly journals The mechanism by which adenosine decreases gluconeogenesis from lactate in isolated rat hepatocytes

1987 ◽  
Vol 246 (2) ◽  
pp. 449-454 ◽  
Author(s):  
A Lavoinne ◽  
H A Buc ◽  
S Claeyssens ◽  
M Pinosa ◽  
F Matray
Keyword(s):  
Ketone Body ◽  
Adenine Nucleotides ◽  
Rat Hepatocytes ◽  
Adenosine Kinase ◽  
Isolated Rat Hepatocytes ◽  
Adenosine Deaminase 2 ◽  
Body Production ◽  
Gluconeogenic Substrates ◽  
Isolated Rat ◽  
Stimulation Of

Incubation of hepatocytes from 24 h-starved rats in the presence of 0.5 mM-adenosine decreased gluconeogenesis from lactate, but not from alanine. The inhibition of gluconeogenesis was associated with a stimulation of ketone-body production and an inhibition of pyruvate oxidation. These metabolic changes were suppressed in the presence of iodotubercidin (an inhibitor of adenosine kinase), but were reinforced in the presence of deoxycoformycin (an inhibitor of adenosine deaminase); 2-chloroadenosine induced no change in gluconeogenesis from lactate. These data indicate that the inhibition of gluconeogenesis by adenosine probably results from its conversion into adenine nucleotides. In the presence of lactate or pyruvate, but not with alanine or asparagine, this conversion resulted in a decrease in the [ATP]/[ADP] ratio in both mitochondrial and cytosolic compartments. Adenosine decreased the Pi concentration with all gluconeogenic substrates.

Acellular liver matrix improves the survival and functions of isolated rat hepatocytes cultured in vitro.

2004 ◽  
Author(s):  
Patrizia Burra ◽  
Silvia Tomat ◽  
Maria Teresa Conconi ◽  
Carlo Macchi ◽  
Francesco P Russo ◽  
...  
Keyword(s):  
Rat Hepatocytes ◽  
Isolated Rat Hepatocytes ◽  
Isolated Rat

scholarly journals Study of hepatotoxins influence in vitro on basic biochemical indicators of liver functional state

2021 ◽  
pp. 15-18
Author(s):  
Liudmyla Maloshtan ◽  
Galyna Storozhenko ◽  
Liubov Galuzinska ◽  
Victoriia Fylymonenko ◽  
Omar Rashid Sadiq
Keyword(s):  
Carbon Tetrachloride ◽  
Biochemical Parameters ◽  
Classical Model ◽  
Rat Hepatocytes ◽  
Isolated Rat Hepatocytes ◽  
Toxic Damage ◽  
Cell Homogenate ◽  
High Doses ◽  
Fluoroquinolone Group

An antimicrobial drug of the fluoroquinolone group, ciprofloxacin, is widely used in Ukraine. However, some researchers have noted the probable hepatotoxicity of this drug with prolonged use or use of high doses of ciprofloxacin. The aim of this study was to compare the effects of carbon tetrachloride, as a classical model of hepatocyte injury, with the effects of ciprofloxacin. The aim of the study was to investigate the biochemical parameters of the liver when simulating toxic damage to hepatocytes with carbon tetrachloride or ciprofloxacin. Materials and methods. The study was carried out on isolated rat hepatocytes, in whose culture medium carbon tetrachloride or ciprofloxacin was added. After incubation in the supernatant and cell homogenate, the activities of marker enzymes of cytolysis were determined: ALT, AST, γ-GTP, LF, LDH, DC and MDA. Results. The introduction of ciprofloxacin into the culture of hepatocytes at a concentration of LC50 caused changes in biochemical parameters similar to those caused by carbon tetrachloride. Thus, an increase in ALT, AST, γ-GTP, LF, LDH, DC and MDA was observed when CCl4 or ciprofloxacin was added to the culture. Conclusion. Incubation of rat hepatocytes with carbon tetrachloride or ciprofloxacin caused an increase in the level of enzymes and lipid peroxidation products. These parameters are indicators of gross changes in cells, which are the result of impaired keto acid formation, impaired redox reactions, impaired glycogen production

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