scholarly journals Some aspects of fatty acid oxidation in isolated fat-cell mitochondria from rat

1975 ◽  
Vol 152 (3) ◽  
pp. 485-494 ◽  
Author(s):  
R D Harper ◽  
E D Saggerson
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Oxidation ◽  
Liver Mitochondria ◽  
Carnitine Palmitoyltransferase ◽  
Acid Oxidation ◽  
Fat Cells ◽  
Fat Cell ◽  
Carnitine Palmitoyltransferase Activity ◽  
Rate Limit ◽  
Carnitine Palmitoyltransferase 1

Mitochondrial were prepared from fat-cells isolated from rat epididymal adipose tissues of fed and 48 h-starved rats to study some aspects of fatty acid oxidation in this tissue. The data were compared with values obtained in parallel experiments with liver mitochondria that were prepared and incubated under identical conditions. 2. In the presence of malonate, fluorocitrate and arsenite, malate, but not pyruvate-bicarbonate, facilitated palmitoyl-group oxidation in both types of mitochondria. In the presence of malate, fat-cell mitochondria exhibited slightly higher rates of palmitoylcarnitine oxidation than liver. Rates of octanoylcarnitine oxidation were similar in liver and fat-cell mitochondria. Uncoupling stimulated acylcarnitine oxidation in liver, but not in fat-cell mitochondria. Oxidation of palmitoyl- and octanoyl-carnitine was partially additive in fat-cell but not in liver mitochondria. Starvation for 48 h significantly decreased both palmitoylcarnitine oxidation and latent carnitine palmitoyltransferase activity in fat-cell mitochondria. Starvation increased latent carnitine palmitoyltransferase activity in liver mitochondria but did not alter palmitoylcarnitine oxidation. These results suggested that palmitoylcarnitine oxidation in fat-cell but not in liver mitochondria may be limited by carnitine palmitoyltransferase 2 activity. 3. Fat-cell mitochondria also differed from liver mitochondria in exhibiting considerably lower rates of carnitine-dependent oxidation of palmitoyl-CoA or palmitate, suggesting that carnitine palmitoyltransferase 1 activity may severely rate-limit palmitoyl-CoA oxidation in adipose tissue.

Carnitine palmitoyltransferase activity and fatty acid oxidation by livers from fetal and neonatal rats

1970 ◽  
Vol 48 (3) ◽  
pp. 288-294 ◽  
Author(s):  
John Augenfeld ◽  
Irving B. Fritz
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Oxidation ◽  
Fetal Liver ◽  
Liver Mitochondria ◽  
Carnitine Palmitoyltransferase ◽  
Acid Oxidation ◽  
Neonatal Rats ◽  
Adult Liver ◽  
Old Rats ◽  
Carnitine Palmitoyltransferase Activity

In liver preparations from fetal rats, the rate of palmitate oxidation to CO2 was approximately one-tenth that found in adult liver homogenates, and the rate of incorporation of labeled palmitate into acetoacetate by livers from fetal animals was approximately one-hundredth of the corresponding rate in liver preparations from neonatal rats. Shortly after birth, the hepatic rate of oxidation of long-chain fatty acids increased greatly, and in liver preparations from 2-day-old rats, the rate was faster than that observed in adult liver preparations.The changes in activity of carnitine palmitoyltransferase in hepatic mitochondria from fetal and neonatal rats were nearly parallel to changes in fatty acid oxidation. Activities in fetal liver preparations were approximately one-tenth those observed in liver mitochondria from adults, while activities in hepatic mitochondria from 2- or 3-day-old rats were slightly greater than those found in adult liver.It was concluded that the rate of hepatic fatty acid oxidation in fetal and neonatal rats, as well as in adult animals, is influenced by the levels of carnitine palmitoyltransferase activity. The possible regulatory role of carnitine and the carnitine palmitoyltransferase reaction in fatty acid oxidation is discussed.

Studies on the control of fatty acid oxidation in liver preparations from chick embryos

1970 ◽  
Vol 48 (4) ◽  
pp. 418-424 ◽  
Author(s):  
D. J. Koerker ◽  
I. B. Fritz
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Oxidation ◽  
Respiratory Control ◽  
Liver Mitochondria ◽  
Acid Oxidation ◽  
Chick Embryos ◽  
Stage Of Development ◽  
Liver Slices ◽  
Hepatic Fatty Acid Oxidation ◽  
Carnitine Palmitoyltransferase Activity

The characteristics and developmental pattern of the metabolic pathway for fatty acid oxidation were investigated in liver slices and mitochondria prepared from chick embryos of varying ages. In 8-day-old chick embryos, hepatic fatty acid oxidation was readily measurable. The incorporation of labelled palmitate into CO2 was increased twofold by carnitine in liver slices of 8-day-old chick embryos but by nearly sixfold to tenfold in tissues prepared from 10- or 12-day-old embryos. A similar increase was seen in the degree of augmentation of ketogenesis induced by carnitine in liver slices prepared from the 10-day-old embryo, suggesting an increased carnitine palmitoyltransferase activity in liver cells during the stage of development from 8 to 10 days. Palmitoyl-CoA was not metabolized in the absence of carnitine, whereas the palmitoyl portion of palmitoylcarnitine readily supported respiration by embryonic chick liver mitochondria. In the presence of adequate amounts of albumin, good respiratory control was evident.The administration of glucose to chick eggs which had previously been incubated for approximately 4.5 days resulted in changes in the metabolism of embryos killed 5 days later, which indicated that tissues of the chick embryo were capable of integrative metabolic adaptations in response to changes in substrate supply.

scholarly journals Specific inhibition of mitochondrial fatty acid oxidation by 2-bromopalmitate and its co-enzyme A and carnitine esters

1972 ◽  
Vol 129 (1) ◽  
pp. 55-65 ◽  
Author(s):  
J. F. A. Chase ◽  
P. K. Tubbs
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Oxidation ◽  
Liver Mitochondria ◽  
Carnitine Palmitoyltransferase ◽  
Acid Oxidation ◽  
Dependent Manner ◽  
Mitochondrial Fatty Acid Oxidation ◽  
Succinate Oxidation ◽  
Mitochondrial Fatty Acid ◽  
Long Chain

1. The CoA and carnitine esters of 2-bromopalmitate are extremely powerful and specific inhibitors of mitochondrial fatty acid oxidation. 2. 2-Bromopalmitoyl-CoA, added as such or formed from 2-bromopalmitate, inhibits the carnitine-dependent oxidation of palmitate or palmitoyl-CoA, but not the oxidation of palmitoylcarnitine, by intact liver mitochondria. 3. 2-Bromopalmitoylcarnitine inhibits the oxidation of palmitoylcarnitine as well as that of palmitate or palmitoyl-CoA. It has no effect on succinate oxidation, but inhibits that of pyruvate, 2-oxoglutarate or hexanoate; however, the oxidation of these substrates (but not of palmitate, palmitoyl-CoA or palmitoyl-carnitine) is restored by carnitine. 4. In damaged mitochondria, added 2-bromopalmitoyl-CoA does inhibit palmitoylcarnitine oxidation; pyruvate oxidation is unaffected by the inhibitor alone, but is impaired if palmitoylcarnitine is subsequently added. 5. The findings have been interpreted as follows. 2-Bromopalmitoyl-CoA inactivates (in a carnitine-dependent manner) a pool of carnitine palmitoyltransferase which is accessible to external acyl-CoA. This results in inhibition of palmitate or palmitoyl-CoA oxidation. A second pool of carnitine palmitoyltransferase, inaccessible to added acyl-CoA in intact mitochondria, can generate bromopalmitoyl-CoA within the matrix from external 2-bromopalmitoylcarnitine; this reaction is reversible. Such internal 2-bromopalmitoyl-CoA inactivates long-chain β-oxidation (as does added 2-bromopalmitoyl-CoA if the mitochondria are damaged) and its formation also sequesters intramitochondrial CoA. Since this CoA is shared by pyruvate and 2-oxoglutarate dehydrogenases, the oxidation of their substrates is depressed by 2-bromopalmitoylcarnitine, unless free carnitine is available to act as a ‘sink’ for long-chain acyl groups. 6. These effects are compared with those reported for other inhibitors of fatty acid oxidation.

scholarly journals Study of some factors controlling fatty acid oxidation in liver mitochondria of obese Zucker rats

1986 ◽  
Vol 239 (1) ◽  
pp. 103-108 ◽  
Author(s):  
P Clouet ◽  
C Henninger ◽  
J Bézard
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Oxidation ◽  
Liver Mitochondria ◽  
Carnitine Palmitoyltransferase ◽  
Urate Oxidase ◽  
Zucker Rats ◽  
Acid Oxidation ◽  
Obese Rats ◽  
Obese Zucker Rats ◽  
Carnitine Palmitoyltransferase I

Livers of genetically obese Zucker rats showed, compared with lean controls, hypertrophy and enrichment in triacylglycerols, indicating that fatty acid metabolism was directed towards lipogenesis and esterification rather than towards fatty acid oxidation. Mitochondrial activities of cytochrome c oxidase and monoamine oxidase were significantly lower when expressed per g wet wt. of liver, whereas peroxisomal activities of urate oxidase and palmitoyl-CoA-dependent NAD+ reduction were unchanged. Liver mitochondria were able to oxidize oleic acid at the same rate in both obese and lean rats. For reactions occurring inside the mitochondria, e.g. octanoate oxidation and palmitoyl-CoA dehydrogenase, no difference was found between both phenotypes. Total carnitine palmitoyl-, octanoyl- and acetyl-transferase activities were slightly higher in mitochondria from obese rats, whereas the carnitine content of both liver tissue and mitochondria was significantly lower in obese rats compared with their lean littermates. The carnitine palmitoyltransferase I activity was slightly higher in liver mitochondria from obese rats, but this enzyme was more sensitive to malonyl-CoA inhibition in obese than in lean rats. The above results strongly suggest that the impaired fatty acid oxidation observed in the whole liver of obese rats is due to the diminished transport of fatty acids across the mitochondrial inner membrane via the carnitine palmitoyltransferase I. This effect could be reinforced by the decreased mitochondrial content per g wet wt. of liver. The depressed fatty acid oxidation may explain in part the lipid infiltration of liver observed in obese Zucker rats.

Sign in / Sign up

Export Citation Format

Share Document