Biomedical subjects

K Waku

Publications and source records attributed to K Waku.

At least 91 records · Page 5Linked to original sources

PubMed1988

Comparison of the HPLC-separated species patterns of phosphatidic acid, CDP-diacylglycerol and diacylglycerol synthesized de novo in rat liver microsomes (a new method).

The species pattern of phosphatidic acid was compared with that of CDP-diacylglycerol and diacylglycerol synthesized de novo by glycerol 3-phosphate acylation in a CoA ester-generating system in liver microsomes. The similarity of the species patterns of phosphatidic acid and CDP-diacylglycerol indicated that the CTP-phosphatidyl cytidylyltransferase showed no selectivity for individual species of its phosphatidic acid substrate. Since the species pattern of diacylglycerol deviated from that of phosphatidic acid, a slight acyl selectivity of the phosphatidic acid phosphohydrolase or a slight inhomogeneity of its substrate pool might be assumed. For the determination of the molecular species of CDP-diacylglycerol, a new method was developed. By incubation of CDP-diacylglycerol with oligonucleate 5'-nucleotidohydrolase (phosphodiesterase), phosphatidic acid was produced. The CDP-diacylglycerol-derived phosphatidic acid was methylated with diazomethane and then separated by reverse-phase HPLC in 15 molecular species.

Animals↗

PubMed1988

Phospholipid analysis of human eosinophils: high levels of alkylacylglycerophosphocholine (PAF precursor).

The phospholipid composition and fatty acid profiles of human eosinophils were studied. Extremely high levels of ether phospholipids were found in this type of cell, such as alkylacylglycerophosphocholine (GPC) and alkenylacylglycerophosphoethanolamine (GPE); these two ether phospholipids accounted for about three-fourths of the choline and ethanolamine glycerophospholipids (CGP and EGP), respectively. Fatty acid analyses revealed that very large portions of arachidonic acid (20:4) were esterified to alkylacyl-GPC (92.0% in CGP) and alkenylacyl-GPE (86.6% in EGP), respectively. While high amounts of alkylacyl-GPC and the abundance of 20:4 in this ether phospholipid have been observed in other types of blood cells of various animals, these percentages for human eosinophils are the highest among such cells. These results suggest that alkyl and alkenyl ether phospholipids play essential roles in human eosinophils in various physiological and pathological conditions.

Eosinophils↗

PubMed1987

Transacylation of lyso platelet-activating factor and other lysophospholipids by macrophage microsomes. Distinct donor and acceptor selectivities.

Rabbit alveolar macrophage microsomes were found to acylate 1-[3H]alkyl-glycero-3-phosphocholine (GPC) (lyso platelet-activating factor) in the absence of any cofactors, indicating the presence of transacylation activity. The transacylation activity was comparable to the activity of acyl-CoA:1-alkyl-GPC acyltransferase. The fatty acyl moieties introduced into 1-[3H]alkyl-GPC from membrane lipids by microsomes were mainly 20:4 (n-6). A very similar acylation profile was observed for the acylation of 1-[3H]alkyl-GPC in intact macrophages, suggesting that the CoA-independent transacylation system plays a very important part in the acylation of 1-[3H]alkyl-GPC in cells. We also confirmed that 14C-labeled 20:4(n-6), 20:5(n-3), 22:4(n-6), and 22:6(n-3) were transferred well from diacyl-GPC to 1-alkyl-GPC in a CoA-independent manner. The transfer rates for 16:0, 18:0, and 18:1 from diacyl-GPC to 1-alkyl-GPC were very low in the presence and absence of CoA. On the other hand, the transfer of 20:4 from diacyl-GPE or diacyl-GPI to 1-alkyl-GPC or 1-acyl-GPC was markedly increased by the addition of CoA. The above results indicate that the transacylation system exhibits distinct donor and acceptor selectivities and CoA dependency. These transacylation reactions could be very important in the regulation of the levels and the availability of lysophospholipids, including lyso platelet-activating factor, and C20 and C22 polyunsaturated fatty acids in living cells.

Acylation↗

PubMed1987

Formation of diacyl and alkylacyl glycerophosphocholine in rabbit alveolar macrophages.

The incorporation of various labeled precursors into alkenylacyl, alkylacyl and diacyl phospholipids in rabbit alveolar macrophages was studied. The incorporation rates of the individual precursors were shown to be quite different among the three subclasses of phospholipids. [3H]Glycerol, [14C]16:0, [14C]18:1, [14C]18:2 and [32P]-orthophosphate were preferentially incorporated into choline glycerophospholipids (CGP), especially into diacyl glycerophosphocholine (GPC), indicating that the de novo synthesis of diacyl GPC is extremely high. Considerable portions of the radioactivities of [14C]16:0, [14C]18:1, [14C]18:2 and [32P]orthophosphate were also found in alkylacyl GPC, the incorporation being higher than or comparable to that in the case of diacyl glycerophosphoethanolamine (GPE). We then examined the activities of cholinephosphotransferase and ethanol-aminephosphotransferase, and found that the activity of cholinephosphotransferase was remarkably high in macrophage microsomes compared with that in microsomes from several other tissues. This suggests that diradylglycerols were preferentially utilized by choline-phosphotransferase, which is consistent with the results obtained for intact cells. We confirmed that a considerably higher amount of diacyl GPC as well as alkylacyl GPC was formed through this enzyme reaction with macrophage microsomes than with brain microsomes. The high formation of alkylacyl GPC could be responsible, at least in part, for the accumulation of this unique ether phospholipid, a stored precursor form of platelet-activating factor in macrophages.

Animals↗

PubMed1987

Lipids of human promyelocytic leukemia cell HL-60: increasing levels of ether-linked phospholipids during retinoic acid-induced differentiation.

Cells of the human promyelocytic leukemia cell line HL-60 as well as HL-60 granulocytes induced in vitro by retinoic acid were examined for lipid composition. One of our original aims was to clarify how human granulocyte (differentiated HL-60 cells) synthesized enough precursors of lipid mediators, such as prostaglandins and/or platelet activating factor. Comparison studies yielded the following results. 1) After granulocyte differentiation, total phospholipid of HL-60 cells decreased to about 70% of that of untreated cells, while the content of triglyceride increased to about 200% of the original level. 2) The subclass composition of ethanolamine-containing glycerophospholipid was greatly altered during differentiation; 1-alkenyl-2-acyl glycerophosphoethanolamine (GPE) increased to 166% of that in the untreated cells, while 1,2-diacyl GPE decreased to 46% of the original value. The resultant profile became very similar to that of human peripheral polymorphonuclear leukocytes. 3) During differentiation, the amount of arachidonic acid stored in both phospholipid and triglyceride of retinoic acid-treated HL-60 cells significantly increased. Its distribution was also modified; arachidonic acid in 1,2-diacyl GPE decreased to 63%, while those of 1-alkenyl-2-acyl GPE, choline-containing glycerophospholipids, and phosphatidylinositol increased to 169, 154, and 153%, respectively. These results suggested that the regulatory mechanism of lipid turnover in HL-60 cells was modified during retinoic acid-induced granulocyte differentiation. The alterations were not enough to explain fully the capability of differentiated HL-60 cells to produce lipid mediators upon stimulation, but they were probably one of the factors that regulate these reactions.

Cell Differentiation↗

PubMed1987

Selective transacylation of 1-O-alkylglycerophosphoethanolamine by docosahexaenoate and arachidonate in rat brain microsomes.

The mechanism involved in the enzymic acylation of 1-[3H]alkylglycero-3-phosphoethanolamine (1-[3H]alkyl-GPE) in brain microsomes was investigated in comparison with the acylation of 1-[3H]alkylglycero-3-phosphocholine (1-[3H]alkyl-GPC). Both the alkyllsophospholipids were acylated without exogenously added cofactors to similar extents. The [14C]arachidonoyl moiety of exogenously added 1-stearoyl-2-[14C]arachidonoyl-GPC was transferred to the alkyllysophospholipids and the transfer was not inhibited by exogenously added free arachidonate. These results indicated that the transferase activity was due to a transacylase that catalyzes the transfer of fatty acids between intact phospholipids. The addition of CoA increased the acylation of 1-[3H]alkyl-GPC two or three times with a high acceptor concentration, and the highest rate of acylation of 1-[3H]alkyl-GPC was observed in the presence of CoA, ATP, and Mg2+. On the other hand, the addition of such cofactors only slightly increased the acylation of 1-[3H]alkyl-GPE. HPLC analysis revealed that docosahexaenoate and arachidonate were transferred to the second position of both [3H]alkyllysophospholipids without cofactors and that other fatty acids were transferred to much lower extents. With the addition of cofactors, the acylation of 1-[3H]alkyl-GPC by both docosahexaenoate and arachidonate increased 1.5-2 times, and high amounts of palmitate, oleate, and linoleate were newly transferred. High amounts of oleate were also transferred to 1-[3H]alkyl-GPE in the presence of cofactors but the acylation by both docosahexaenoate and arachidonate scarcely increased on the addition of these cofactors.(ABSTRACT TRUNCATED AT 250 WORDS)

Acylation↗

PubMed1986

Improved procedure for the separation of the molecular species of dimethylphosphatidate by high-performance liquid chromatography.

We describe a rapid and efficient high-performance liquid chromatographic (HPLC) procedure for the separation of the molecular species of dimethylphosphatidic acid derived from phosphatidylcholine, which naturally occurs in mammalian tissues. The separation was accomplished on a reversed-phase column after derivatization of phosphatidylcholine to dimethylphosphatidate by means of phospholipase D and subsequent diazomethane treatments. Separation of the major molecular species of dimethylphosphatidate by reversed-phase HPLC was achieved within 40 min. Dimethylphosphatidate from rat liver phosphatidylcholine was resolved into twelve separate peaks. Thirteen different molecular species in rat liver phosphatidylcholine were identified by gas chromatographic determination. This improved method is applicable to studies on the metabolism of the phosphate group of the molecular species of phospholipid of a variety of tissues using a radioactive precursor.

Animals↗

PubMed1986

Separation of dimethylphosphatidates of alkylacyl glycerophosphocholine and their molecular species by high-performance liquid chromatography.

A high-performance liquid chromatography (HPLC) method for separation of the alkylacyl and diacyl analogs of choline glycerophospholipids (CGP) of guinea pig polymorphonuclear leukocytes and their molecular species is described. CGP were hydrolyzed with phospholipase D and then methylated with diazomethane to convert them to dimethylphosphatidates. The dimethylphosphatidates were then separated into the alkylacyl and diacyl subclasses by HPLC on a silica gel column within 15 min. The alkylacyl and diacyl analogs were then separated into individual molecular species by reverse-phase HPLC. Dimethylphosphatidates were resolved into 15 separate peaks, and 11-16 different molecular species of alkylacyl and diacyl glycerophosphocholines were identified on gas-liquid chromatography. The present results indicate that the CGP of polymorphonuclear leukocytes are composed of 27 major molecular species. In the alkylacyl subclass, the most predominant species was the 16:0-18:2 species (32%), followed by the 18:1-18:2 (18%), 16:0-16:0 (16%), and 16:0-18:1 (15%) species. The diacyl type consisted mainly of species with 18:2 at the 2-position, such as the 16:0-18:2, 18:0-18:2, and 18:1-18:2 species, the total percentage of which was 57%.

Animals↗

PubMed1986

Relative degradation of different arachidonoyl molecular species of choline glycerophospholipids in opsonized zymosan-stimulated rabbit alveolar macrophages.

The relative degradation of arachidonoyl molecular species of glycerophospholipids prelabeled with [3H]20:4 caused by opsonized zymosan was studied in rabbit alveolar macrophages using a recently developed high-performance liquid chromatographic method. The opsonized zymosan caused the release of [3H]20:4 only from choline glycerophospholipids, no significant changes being observed in the radioactivities of other glycerophospholipids and triacylglycerol. Choline glycerophospholipids were resolved into seven arachidonoyl molecular species, which differed as to the alkyl ether or acyl residue bound at the 1-position, by high-performance liquid chromatography. Arachidonate was predominantly located in the alkyl type having 16:0 at the 1-position which comprised more than half of the total arachidonoyl molecular species of choline glycerophospholipids. The radioactivities of all arachidonoyl molecular species of choline glycerophospholipids, except for the 18:2-20:4 and 18:1-20:4 species of diacylglycerophosphocholine, decreased to 80-85% of the control values as a result of the challenge with opsonized zymosan for 1 h. However, 50% of the released 20:4 came from the 16:0-20:4 species of alkylacylglycerophospholipids, which were the most predominant species of choline glycerophospholipids. The present results indicate that the 16:0-20:4 species of alkylacylglycerophosphocholine is a significant source of arachidonate and 1-O-alkyl-2-lysoglycerophosphocholine, the precursor of the platelet-activating factor, relative to other arachidonoyl species in activated alveolar macrophages.

Animals↗

PubMed1986

Selective acylation of alkyllysophospholipids by docosahexaenoic acid in Ehrlich ascites cells.

Ehrlich ascites cells were cultured with 1-O-[3H]alkylglycero-3-phosphoethanolamine (1-[3H]alkyl-GPE) or 1-O-[3H]alkylglycero-3-phosphocholine (1-[3H]alkyl-GPC) to reveal the selective retention of polyunsaturated fatty acids at second position of ether-containing phospholipids. Although small percentages of the lysophospholipids were degraded into long-chain alcohol, both alkyllyso-GPE and -GPC were acylated at the rate of approximately 2 nmol/30 min per 10(7) cells. Alkylacylacetylglycerols were prepared from the acylated products by phospholipase C treatment, acetylation and TLC, and fractionated according to the degree of unsaturation by AgNO3-TLC. The distribution of the radioactivity among the subfractions indicated that both alkyllysophospholipids were mainly esterified by docosahexaenoic acid and to a somewhat lesser extent by arachidonic acid. The selectivity for docosahexaenoic acid in the esterification of 1-alkyl-GPE was much stronger than in that of 1-alkyl-GPC. Although acyl-CoA: 1-alkyl-glycerophosphoethanolamine acyltransferase activity of Ehrlich cell microsomes with arachidonoyl-CoA and docosahexaenoyl-CoA as acyl donors was negligible compared with the acyl-CoA:1-alkyl-glycerophosphocholine acyltransferase activity, a significant amount of 1-alkyl-GPE was acylated in the microsomes without exogenously added acyl-CoA. HPLC analysis revealed that docosahexaenoic acid and arachidonic acid were mainly esterified by the microsomal transferase. Acylation of 1-alkyl-GPC with docosahexaenoic acid and arachidonic acid was also observed in the absence of added acyl-CoA, but the activity was lower than that for 1-alkyl-GPE. Although the source of the acyl donor in the acylation has not been determined, the acylation is probably due to the direct transfer of acyl groups between intact phospholipids. The above results provided the first evidence that the lysophospholipid acyltransferase system including the transacylase activity participates in the selective retention of docosahexaenoic acid in intact cells and a cell free system.

Acylation↗

PubMed1986

Synthesis of the dipalmitoyl species of diacyl glycerophosphocholine by rabbit alveolar macrophages.

The distribution of radioactivity among the molecular species of diacyl glycerophosphocholine of rabbit alveolar macrophages was determined after incubation with [3H]glycerol and 1-[14C]palmitoyl-sn-glycero-3-phosphocholine. The highest percentage of radioactivity of [3H]glycerol was found in the dipalmitoyl species (35% of the total) followed by the 1-palmitoyl-2-linoleoyl (23.6%) and 1-stearoyl-2-linoleoyl plus 1-palmitoyl-2-oleoyl species (19.7%) during the first 30 min incubation. The radioactivity of the dipalmitoyl species reached a maximum at 120 min incubation and decreased thereafter, although the radioactivities of other molecular species still increased. In contrast to the [3H]glycerol labeling, only 4% of the total radioactivity in diacyl glycerophosphocholine derived from 1-[14C]palmitoyl glycerophosphocholine was found in the dipalmitoyl species; 80% of the radioactivity was located in the 1-palmitoyl-2-arachidonoyl species at 10 min incubation. The present results indicate that the dipalmitoyl species of diacyl glycerophosphocholine are synthesized predominantly via a de novo pathway and not the deacylation-reacylation pathway in rabbit alveolar macrophages.

1,2-Dipalmitoylphosphatidylcholine↗

PubMed1986

Effect of clofibric acid on the molecular species composition of diacyl glycerophosphocholine of rat liver microsomes.

The effect of administering p-chlorophenoxyisobutyric (clofibric) acid to rats on the molecular species composition of diacyl-glycerophosphocholine (GPC) of rat liver microsomes was studied. Microsomal choline glycerophospholipids were converted to 1,2-diradyl-3-acetylglycerol and were separated into molecular species by reverse-phase high performance liquid chromatography. Diacyl-GPC consisted of 17 different molecular species. The predominant species were arachidonoyl derivatives, such as 18:0-20:4 (22.2% of the total) and 16:0-20:4 (22.0%). Administration of clofibric acid to rats caused a marked increase in 16:0-18:1 species of diacyl-GPC from 8% to 30%, making these the predominant species of diacyl-GPC in clofibric acid-fed rats. Also, a significant decrease (50% of controls) in 18:0-18:2 and 18:0-20:4 species was observed, whereas the decrease in molecular species containing 16:0 at the 1-position such as 16:0-18:2 and 16:0-20:4 was small (approximately 85% of control). The results show that clofibric acid caused marked changes in the molecular species composition of diacyl-GPC. The participation of 1-acyl-GPC acyltransferase and stearoyl-CoA desaturase in the regulation of the molecular species composition of diacyl-GPC is discussed.

Acyltransferases↗

PubMed1986

Protection against cadmium toxicity by zinc: decrease in the Cd-high molecular weight protein fraction in rat liver and kidney on Zn pretreatment.

The amounts of cadmium, associated with high molecular weight proteins, metallothionein and low molecular weight fractions obtained on Sephadex G-75 gel filtration, were determined in the liver and kidneys of rats treated with Cd. When rats were pretreated with zinc 24 h prior to the Cd injection, Cd associated with the high molecular weight proteins was decreased in both the liver and kidneys. Although the Cd concentration in the liver was increased, the liver showed less morphological damage in Zn-pretreated rats. The above results suggest that Cd-toxicity toward the liver and kidneys may be related to the accumulation of Cd in the high molecular weight proteins.

Alkaline Phosphatase↗

PubMed1986

Selective incorporation of various C-22 polyunsaturated fatty acids in Ehrlich ascites tumor cells.

Three 14C-labeled 22-carbon polyunsaturated fatty acids, 7,10,13,16-[14C]docosatetraenoic acid (22:4(n-6)), 7,10,13,16,19-[14C]docosapentaenoic acid (22:5(n-3)), and 4,7,10,13,16,19-[14C]docosahexaenoic acid (22:6(n-3)), were compared with [3H]arachidonic acid (20:4(n-6] and [14C]linoleic acid (18:2(n-6)) to characterize their incorporation into the lipids of Ehrlich ascites cells. The relatively rapid incorporation of the labeled 22-carbon acids into phosphatidic acid indicated that substantial amounts of these acids may be incorporated through the de novo pathway of phospholipid synthesis. In marked contrast to 20:4(n-6), the 22-carbon acids were incorporated much less into choline glycerophospholipids (CGP) and inositol glycerophospholipids (IGP). No selective preference was apparent for the (n-3) or (n-6) type of fatty acids. The amounts of the acids incorporated into diacylglycerophosphoethanolamine were in the order of: 22:6(n-3) greater than 20:4(n-6) much greater than 22:5(n-3) greater than or equal to 22:4(n-6) greater than 18:2(n-6), whereas for alkylacylglycerophosphoethanolamine they were in the order of: 22:4(n-6) greater than 22:6(n-3) greater than 22:5(n-3) much greater than 20:4(n-6) greater than 18:2(n-6). Of the mechanisms possibly responsible for the selective entry of 22-carbon acids into ethanolamine glycerophospholipids, the most reasonable explanation was that the cytidine-mediated ethanolamine phosphotransferase may have a unique double selectivity: for hexaenoic species of diacylglycerol and for 22-carbon polyunsaturated fatty acid-containing species of alkylacylglycerol. The relative distribution of fatty acids between newly incorporated and already maintained lipid classes suggested that IGP may function in Ehrlich cells as an intermediate pool for the retention of polyunsaturated fatty acids in glycerolipids.

Animals↗

PubMed1985

Transacylation of 1-O-alkyl-SN-glycero-3-phosphocholine (lyso platelet-activating factor) and 1-O-alkenyl-SN-glycero-3-phosphoethanolamine with docosahexaenoic acid (22:6 omega 3).

[14C]22:6 (docosahexaenoic acid) was rapidly incorporated into cellular lipids in rabbit alveolar macrophages. After removal of free [14C]22:6, the radioactivity in diacyl-glycerophosphocholine (GPC) gradually decreased with a concomitant increase in [14C]22:6 in alkylacyl-GPC and alkenylacyl-glycerophosphoethanolamine (GPE), indicating that [14C]22:6 was transferred from diacyl-GPC to these ether lipid fractions. In fact, macrophage microsomes were shown to catalyze the transfer of [14C]22:6 from exogenously added diacyl-GPC to 1-alkyl-GPC (lyso platelet-activating factor) and 1-alkenyl-GPE. These results are the first evidence for the involvement of the transacylation system in the metabolism of C22 polyunsaturated fatty acids and lyso platelet-activating factor.

Acylation↗

PubMed1985

Heterogeneity in the metabolism of the arachidonoyl molecular species of glycerophospholipids of rabbit alveolar macrophages. The interrelationship between metabolic activities and chemical structures of the arachidonoyl molecular species.

The relative incorporation of [3H]arachidonic acid (20:4) into individual molecular species containing 20:4 at the 2 position (18:1-20:4, 16:0-20:4 and 18:0-20:4 species) of diacyl and ether-linked glycerophosphocholine, glycerophosphoethanolamine and glycerophosphoinositol of rabbit alveolar macrophages has been measured by reversed-phase high-performance liquid chromatography (HPLC). The rate of incorporation of [3H]20:4 into the molecular species of glycerophospholipids was greatly influenced by their structures. The reversed-phase HPLC analysis allowed elucidation of the influence of structural differences, such as the nature of the polar head group, the fatty chain at the 1 position and the chemical form of the bond of the fatty chain attached at the 1 position on the uptake of [3H]20:4 by comparison of the specific radioactivities of arachidonoyl molecular species having the same structures, except that one of the three kinds of moiety was different. The specific radioactivities of the molecular species containing choline head groups were significantly higher than those containing ethanolamine and inositol moieties. The specific radioactivities of diacyl molecular species were considerably higher than those of ether-linked molecular species. The nature of the fatty chain attached at the 1 position also influenced the uptake of [3H]20:4 into glycerophospholipids. The arachidonoyl molecular species containing 18:1 at the 1 position were preferentially labelled with [3H]20:4 as compared to the corresponding 16:0-20:4 and 18:0-20:4 species either of diacyl or ether-linked glycerophospholipids. The present results suggest that the acyltransferase involved in the incorporation of 20:4 into glycerophospholipids has selectivity for the structures of glycerophospholipids and the order of selectivity of this enzyme for the arachidonoyl molecular species, deduced in the present experiments, was as follows: choline head group greater than ethanolamine and inositol groups, acyl bond greater than ether and vinyl ether bonds, 18:1 fatty chain greater than 16:0 and 18:0 fatty chains at the 1 position. Comparison of the metabolic activities of all major arachidonoyl molecular species of glycerophospholipids having a single structure is reported here for the first time.

Animals↗

PubMed1985

Selective synthesis of the hexaenoic molecular species of ether-linked glycerophosphoethanolamine of Ehrlich ascites tumor cells.

In a previous study [Waku, K. and Nakazawa, Y. (1978) Eur. J. Biochem. 88, 489-494], we observed the rapid turnover rate of the molecular species of alkylacyl glycerophosphoethanolamine (Gro-P-Etn) containing docosahexaenoic acid and the high selectivity for this molecular species of ethanolamine phosphotransferase was suggested. To clarify this point, the incorporation of [14C]ethanolamine and [14C]CDP-ethanolamine into the individual molecular species of alkenylacyl, alkylacyl and diacyl Gro-P-Etn has been determined in Ehrlich ascites tumor cells. [14C]Ethanolamine was highly incorporated into the pentaenoic + hexaenoic species of alkenylacyl, alkylacyl and diacyl Gro-P-Etn, whereas incorporation of [14C]ethanolamine into molecular species other than the pentaenoic + hexaenoic species was quite low. The selectivity of ethanolamine phosphotransferase to form the molecular species of alkylacyl and diacyl Gro-P-Etn was examined by incubation of [14C]CDP-ethanolamine and microsomes of Ehrlich ascites tumor cells. The incorporation of [14C]CDP-ethanolamine was found to occur most into the pentaenoic + hexaenoic species of both alkylacyl and diacyl Gro-P-Etn. The present results suggest that the pentaenoic + hexaenoic species are preferentially synthesized among the various kinds of molecular species of alkylacyl and diacyl Gro-P-Etn by the ethanolamine phosphotransferase in Ehrlich ascites tumor cells.

Acylation↗

PubMed1985

Acceleration of rat liver phospholipid metabolism after long-term cadmium administration.

Male Wistar rats, 6 weeks old, were allowed free access to water containing cadmium chloride at a concentration of 250 ppm as cadmium (Cd) for 6 and 12 months. The growth, as measured by body weight of Cd-treated rats, was significantly retarded. Electron microscopic studies revealed the appearance of small vacuoles in the cytoplasm, and involution of the rough endoplasmic reticulum (RER) in both the liver and whole kidney. When radioactive precursors of phospholipids, H3(32)PO4 and [1(3)-H]glycerol, were injected (ip) into cd-treated rats, the incorporation of 32P into phosphatidylcholine (PC) in the liver was increased 3.2- and 5.8-fold after 6- and 12-month Cd administration, respectively, and that of 3H into PC was also increased 2.3- and 2.2-fold after 6- and 12-month Cd administration, respectively. In the kidney, however, the incorporation rates of these radioactive precursors were little affected by long-term Cd administration. In the liver of rats treated with Cd for 6 and 12 months, the activity of CDP-choline:cholinephosphotransferase was increased by 20-30% over the control. It was shown that de novo synthesis of PC, which is a major constituent of biological membranes, was accelerated by long-term Cd administration in the liver but not in the kidney. These results suggest the possibility of regenerating the membranes in damaged hepatocytes after 6 and 12 months of Cd administration.

Animals↗