Hepatic lactate uptake is enhanced by low pH at low lactate concentrations in perfused rat liver

1986 ◽  
Vol 70 (1) ◽  
pp. 19-22 ◽  
Author(s):  
Leif Sestoft ◽  
Michael O. Marshall
Keyword(s):  
Linear Function ◽  
Rat Liver ◽  
Lactate Concentration ◽  
Low Ph ◽  
Perfused Liver ◽  
Perfused Rat Liver ◽  
Effect Of Ph ◽  
Lactate Uptake

1. The effect of pH on lactate uptake was studied in perfused liver of rats starved for 48 h. 2. At both low pH (6.8) and normal pH (7.4) lactate uptake was a linear function of lactate concentration in input medium in the range 0.4–1.5 mmol/l. 2. In the lower concentration range (0.4–0.8 mmol/l) the rate of lactate uptake was 30% higher at pH 6.8 than at pH 7.4. 4. At pH 6.8 lactate uptake was independent of whether Pco2 was 2.7 or 5.3 kPa. 5. We suggest the increased rate of lactate uptake at low pH and concentrations lower than 0.8 mmol/l was due to the stimulatory effect of H+ on the lactate carrier.

Biliary excretion of dihydro-11-keto-progesterone-4-C14 by isolated perfused liver

1964 ◽  
Vol 207 (5) ◽  
pp. 1030-1034 ◽  
Author(s):  
G. F. Leong ◽  
D. M. Cazes ◽  
M. L. Berliner ◽  
D. L. Berliner
Keyword(s):  
Rat Liver ◽  
Biliary Excretion ◽  
Half Life ◽  
Water Soluble ◽  
Isolated Perfused Rat Liver ◽  
Perfused Liver ◽  
Rapid Rate ◽  
Perfused Rat Liver ◽  
Bile Formation ◽  
Entire Study

The rates of biliary excretion of dihydro-11-keto-progesterone-4-C14 and of its metabolites were studied in the isolated perfused rat liver. The half-life of this steroid in the perfusing blood was 2.5 min, and at 40 min about 75% of the injected steroid had been excreted in bile. Formation of water-soluble steroids (WS St) took place at a rapid rate and by 60 min 100% of the steroids in blood were found to be water soluble. During the entire study the steroids excreted in bile were water soluble and accounted for 97.2–100% (avg. 98.2%). No dihydro-11-keto-progesterone was found to be excreted in the bile. The rate of disappearance from the blood, excretion in the bile, and degree of formation of WS St of this compound when compared with corticosterone and cortisol shows the following pattern: dihydro-11-keto-progesterone > corticosterone > cortisol.

Coordinated regulation of hepatic glycogen formation in perfused rat liver by glucose and lactate

1994 ◽  
Vol 266 (4) ◽  
pp. E583-E591 ◽  
Author(s):  
Z. Zhang ◽  
J. Radziuk
Keyword(s):  
Rat Liver ◽  
Dose Response ◽  
Glycogen Synthesis ◽  
Hepatic Glycogen ◽  
Perfused Rat Liver ◽  
Response Curves ◽  
Liver Preparation ◽  
Lactate Uptake ◽  
Glucose Output ◽  
Glycogen Formation

Lactate has been found to enhance the formation of glycogen from both glucose and lactate as substrate (Z. Zhang and J. Radziuk. Biochem. J. 280: 415–419, 1991). To evaluate the relative importance of its role as substrate and regulatory factor, a dual dose-response evaluation was done by adding variable amounts of glucose and lactate to the medium in a recirculating perfused rat liver preparation. Nine groups of perfusions were performed utilizing three different levels of carbon infusion into the system: 0.25, 1.0, and 2.0 mg/min. These levels of carbon infusion were further subdivided into different relative amounts of glucose and lactate. Lactate uptake by the perfused liver was linearly related with net glucose output, regardless of the glucose concentrations. In contrast to this, the effect of lactate uptake on the rate of glycogen synthesis is saturable. Moreover, the rate of glycogen formation at which this saturation occurs is dependent only on the mean perfusate glucose concentration. The highest amount of glycogen formed in a 2-h period was 50 +/- 7 mg and the lowest 3.4 +/- 0.3 mg. A family of dose-response curves was generated describing this dual dependence of glycogen formation (both direct and gluconeogenetic pathways) on lactate and glucose.

The Effect of Simulated Metabolic Acidosis on Intracellular pH and Lactate Metabolism in the Isolated Perfused Rat Liver

1973 ◽  
Vol 45 (4) ◽  
pp. 543-549 ◽  
Author(s):  
M. H. Lloyd ◽  
R. A. Iles ◽  
B. R. Simpson ◽  
J. M. Strunin ◽  
J. M. Layton ◽  
...  
Keyword(s):  
Metabolic Acidosis ◽  
Intracellular Ph ◽  
Rat Liver ◽  
Extracellular Ph ◽  
Isolated Perfused Rat Liver ◽  
Perfused Rat Liver ◽  
Lactate Metabolism ◽  
Lactate Output ◽  
Lactate Uptake ◽  
The Relationship

1. The relationship between extracellular pH (pHe), intracellular pH (pHi) and lactate uptake was studied in the isolated perfused rat liver during simulated metabolic acidosis. 2. pHi fell to a considerably less extent than pHe when the latter was decreased from pH 7·4 to 6·7. 3. The liver took up lactate when pHi was greater than 7·0; at lower values of pHi lactate output occurred. 4. The relevance of these observations to the control of hepatic pHi and lactate metabolism is discussed.

Effect of Varying Pco2 on Intracellular pH and Lactate Consumption in the Isolated Perfused Rat Liver

1978 ◽  
Vol 55 (2) ◽  
pp. 175-181 ◽  
Author(s):  
P. G. Baron ◽  
R. A. Iles ◽  
R. D. Cohen
Keyword(s):  
Intracellular Ph ◽  
Rat Liver ◽  
Isolated Perfused Rat Liver ◽  
Perfused Rat Liver ◽  
Lactate Metabolism ◽  
Isolated Rat Liver ◽  
Buffering Effect ◽  
Lactate Uptake ◽  
Lactate Consumption ◽  
Isolated Rat

1. The effects of varying Pco2 on lactate uptake and intracellular pH (pHl) were studied in the isolated rat liver perfused with differing concentrations of lactate. 2. In general, pHl and lactate uptake are inversely related to Pco2, and pHl and lactate uptake are directly related to each other, but the quantitative aspects and significance of these relationships vary with the availability of lactate. A model of hepatic lactate metabolism is proposed which may account for the quantitative variation. 3. The metabolism of lactate within the hepatocyte exerts a destabilizing effect on hepatocyte cell pH, in contrast to the buffering effect seen in predominantly glycolytic tissues. 4. An attempt is made to relate the findings to the disturbances of lactate metabolism in clinical respiratory failure.

scholarly journals Rates of ketone-body formation in the perfused rat liver

1969 ◽  
Vol 112 (5) ◽  
pp. 595-600 ◽  
Author(s):  
H. A. Krebs ◽  
Patricia G. Wallace ◽  
R. Hems ◽  
R. A. Freedland
Keyword(s):  
Fatty Acids ◽  
Rat Liver ◽  
Ketone Bodies ◽  
Short Chain Fatty Acids ◽  
Diabetic Rats ◽  
Isolated Perfused Rat Liver ◽  
Perfused Liver ◽  
Perfused Rat Liver ◽  
Normal Range ◽  
Physiological Value

1. The rates of formation of acetoacetate and β-hydroxybutyrate by the isolated perfused rat liver were measured under various conditions. 2. The rates found after addition of butyrate, octanoate, oleate and linoleate were about 100μmoles/hr./g. wet wt. in the liver of starved rats. These rates are much higher than those found with rat liver slices. 3. The differences between the rates given by slices and by the perfused organ were much higher with the long-chain than with short-chain fatty acids. The increments caused by oleate and linoleate were 12 and 16 times as large in the perfused organ as in the slices, whereas the increments caused by butyrate and octanoate were about four times as large. 4. The rates of ketogenesis in the unsupplemented perfused liver of well-fed rats, and the increments caused by the addition of fatty acids, were about half of those in the liver from starved rats. 5. The value of the [β-hydroxybutyrate]/[acetoacetate] ratio of the medium was raised by octanoate, oleate and linoleate. 6. Carnitine did not significantly accelerate ketogenesis from fatty acids. 7. Oleate formed up to 82% of the expected yield of ketone bodies. 8. In the liver of alloxan-diabetic rats the endogenous rates of ketogenesis were raised, in some cases as high as in the liver from starved rats, after addition of oleate. 9. On addition of either β-hydroxybutyrate or acetoacetate to the perfusion medium the liver gradually adjusted the [β-hydroxybutyrate]/[acetoacetate] ratio towards the normal range. 10. The [β-hydroxybutyrate]/[acetoacetate] ratio of the medium was about 0·4 when slices were incubated, but near the physiological value of 2 when the liver was perfused. 11. The experiments demonstrate that for the study of ketogenesis slices are in many ways grossly inferior to the perfused liver.

The Effect of Combined Ischaemia and Acidosis on Lactate Uptake and Gluconeogenesis in the Perfused Rat Liver

1981 ◽  
Vol 60 (5) ◽  
pp. 537-542 ◽  
Author(s):  
R. A. Iles ◽  
R. D. Cohen ◽  
P. G. Baron
Keyword(s):  
Lactic Acid ◽  
Rat Liver ◽  
Hepatic Uptake ◽  
Strenuous Exercise ◽  
Perfused Rat Liver ◽  
Lactate Uptake ◽  
Glucose Output ◽  
Rat Livers

1. Perfused rat livers were subjected to an acid perfusate and varying degrees of ischaemia in an attempt to simulate the conditions of strenuous exercise or shock. 2. Lactate uptake and glucose output from the liver decreased during moderate ischaemia alone and more so when, in addition, the perfusate was made acidic. 3. Hepatic ATP and ADP content increased in the presence of an acid perfusate. 4. It is concluded that both ischaemia and acidosis may contribute to the diminished hepatic uptake of lactic acid in strenuous exercise and shock.

Metabolic effects of acetate in perfused rat liver studies on ketogenesis, glucose output, lactate uptake and lipogenesis

1982 ◽  
Vol 716 (3) ◽  
pp. 290-297 ◽  
Author(s):  
Alan M. Snoswell ◽  
Rodney P. Trimble ◽  
Richard C. Fishlock ◽  
Gerald B. Storer ◽  
David L. Topping
Keyword(s):  
Rat Liver ◽  
Metabolic Effects ◽  
Perfused Rat Liver ◽  
Lactate Uptake ◽  
Glucose Output
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