Pyruvate carboxylation in glutamine synthesis from alanine by isolated guinea-pig renal cortical tubules

1988 ◽  
Vol 412 (1-2) ◽  
pp. 7-11 ◽  
Author(s):  
Christian Michoudet ◽  
Guy Martin ◽  
Gabriel Baverel
Keyword(s):  
Guinea Pig ◽  
Pyruvate Carboxylation ◽  
Glutamine Synthesis

scholarly journals Glutamine synthesis from aspartate in guinea-pig renal cortex

1990 ◽  
Vol 268 (2) ◽  
pp. 437-442 ◽  
Author(s):  
G Baverel ◽  
G Martin ◽  
C Michoudet
Keyword(s):  
Glutamine Synthetase ◽  
Guinea Pig ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Tricarboxylic Acid Cycle ◽  
Kidney Cortex ◽  
Carbon And Nitrogen ◽  
Ammonia Release ◽  
Glutamine Synthesis ◽  
Methionine Sulphoximine ◽  
Main Carbon

1. Glutamine was found to be the main carbon and nitrogen product of the metabolism of aspartate in isolated guinea-pig kidney-cortex tubules. Glutamate, ammonia and alanine were only minor products. 2. Carbon-balance calculations and the release of 14CO2 from [U-14C]aspartate indicate that oxidation of the aspartate carbon skeleton occurred. 3. A pathway involving aspartate aminotransferase, glutamate dehydrogenase, glutamine synthetase, phosphoenolpyruvate carboxykinase, pyruvate kinase, pyruvate dehydrogenase and enzymes of the tricarboxylic acid cycle is proposed for the conversion of aspartate into glutamine. 4. Evidence for this pathway was obtained by: (i) inhibiting aspartate removal by amino-oxyacetate, an inhibitor of transaminases, (ii) the use of methionine sulphoximine, an inhibitor of glutamine synthetase, which induced a large increase in ammonia release from aspartate, (iii) the use of quinolinate, an inhibitor of phosphoenolpyruvate carboxykinase, which inhibited glutamine synthesis from aspartate, (iv) the use of alpha-cyano-4-hydroxycinnamate, an inhibitor of the mitochondrial transport of pyruvate, which caused an accumulation of pyruvate from aspartate, and (v) the use of fluoroacetate, an inhibitor of aconitase, which inhibited glutamine synthesis with concomitant accumulation of citrate from aspartate.

scholarly journals Release and fixation of CO2 by guinea-pig kidney tubules metabolizing aspartate

1992 ◽  
Vol 284 (3) ◽  
pp. 697-703
Author(s):  
G Martin ◽  
C Michoudet ◽  
N Vincent ◽  
G Baverel
Keyword(s):  
Guinea Pig ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Co2 Fixation ◽  
Carbon Oxidation ◽  
Kidney Tubules ◽  
Pig Kidney ◽  
Glutamine Synthesis ◽  
Oxoglutarate Dehydrogenase

1. The metabolism of L-[U-14C]aspartate, L-[1-14C]aspartate and L-[4-14C]aspartate was studied in isolated guinea-pig kidney tubules. 2. Oxidation of C-1 plus that of C-4 of aspartate accounted for 90-92% of the CO2 released from aspartate, whereas oxidation of the inner carbon atoms of aspartate (which occurs beyond the 2-oxoglutarate dehydrogenase step) represented only 8-10% of aspartate carbon oxidation. 3. The formation of [1-14C]glutamine and [1-14C]glutamate from [1-14C]aspartate and [4-14C]aspartate indicated that about one-third of the oxaloacetate synthesized from aspartate underwent randomization at the level of fumarate. 4. With [U-14C]aspartate as substrate, the percentage of the C-1 of glutamate and glutamine found radiolabelled after 60 min of incubation was 92.7% and 47.5% in the absence and the presence of bicarbonate respectively. 5. That CO2 fixation occurred at high rates in the presence of bicarbonate was demonstrated by incubating tubules with aspartate plus [14C]bicarbonate; under this condition, the label fixed was found in C-1 of glutamate, glutamine and aspartate, as well as in C-4 of aspartate, demonstrating not only randomization of aspartate carbon but also aspartate resynthesis secondary to oxaloacetate cycling via phosphoenolpyruvate carboxykinase, pyruvate kinase and pyruvate carboxylase. 6. The importance of CO2 fixation in glutamine synthesis from aspartate is discussed in relation to the possible role of the guinea-pig kidney in systemic acid-base regulation in vivo.

scholarly journals Glutamine synthesis from glucose and ammonium chloride by guinea-pig kidney tubules

1994 ◽  
Vol 297 (1) ◽  
pp. 69-74 ◽  
Author(s):  
C Michoudet ◽  
M F Chauvin ◽  
G Baverel
Keyword(s):  
Glucose Metabolism ◽  
Guinea Pig ◽  
Carbon Skeleton ◽  
Kidney Cortex ◽  
Physiological Concentration ◽  
Pig Kidney ◽  
Glucose Carbon ◽  
Glutamine Synthesis ◽  
Stimulation Of

1. At a physiological concentration (5 mM), glucose was found to be metabolized by isolated kidney cortex tubules prepared from fed guinea pigs. 2. The release of 14CO2 from [U-14C]glucose indicated that oxidation of the glucose carbon skeleton represented about 50% of the glucose removed; significant amounts of lactate and glutamine also accumulated. 3. Addition of 0.1-10 mM NH4Cl led to a dose-dependent stimulation of glucose metabolism which was accompanied by a large increase in lactate and glutamine accumulation and, to a lesser extent, in glucose oxidation. 4. Comparison of the release of 14CO2 from [1-14C]- and [6-14C]glucose indicates that, in both the absence and the presence of NH4Cl, the pentose phosphate shunt was only a minor pathway of glucose metabolism. 5. The central role of pyruvate carboxylase in the conversion of glucose carbon into glutamine carbon was demonstrated by using a bicarbonate-free medium and measuring the fixation of 14CO2 from [14C]bicarbonate, which was recovered mostly at C-1 of glutamine plus glutamate. 6. The NH4Cl-induced stimulation of glucose removal was secondary not only to increased glutamine synthesis, as shown by the effect of methionine sulphoximine, an inhibitor of glutamine synthetase, but also to the stimulation of phosphofructokinase activity by NH4Cl. 7. Renal arterio-venous difference measurements revealed that, in vivo, the guinea-pig kidney removed glucose from the circulating blood, which suggests that glucose carbon may contribute to the carbon skeleton of the glutamine released by this organ.

Effect of Contraceptive Steroids on the Endometrium of Guinea Pig: SEM study

1977 ◽  
Vol 35 ◽  
pp. 668-669
Author(s):  
Mai M. Said ◽  
Ramesh K. Nayak ◽  
Randall E. McCoy
Keyword(s):  
Guinea Pig ◽  
Reproductive Tract ◽  
Three Dimensional ◽  
Female Reproductive Tract ◽  
Human Female ◽  
Surface Ultrastructure ◽  
Transmission Electron ◽  
Sem Study ◽  
Uterine Mucosa ◽  
Group 1

Burgos and Wislocki described changes in the mucosa of the guinea pig uterus, cervix and vagina during the estrous cycle investigated by transmission electron microscopy. More recently, Moghissi and Reame reported the effects of progestational agents on the human female reproductive tract. They found drooping and shortening of cilia in norgestrel and norethindrone- treated endometria. To the best of our knowledge, no studies concerning the effects of mestranol and norethindrone given concurrently on the three-dimensional surface features on the uterine mucosa of the guinea pig have been reported. The purpose of this study was to determine the effect of mestranol and norethindrone on surface ultrastructure of guinea pig uterus by SEM.Seventy eight animals were used in this study. They were allocated into two groups. Group 1 (20 animals) was injected intramuscularly 0.1 ml vegetable oil and served as controls.

Ultrastructure and Drug Metabolism in the Developing Guinea Pig

1973 ◽  
Vol 31 ◽  
pp. 538-539
Author(s):  
W. Kuenzig ◽  
M. Boublik ◽  
J.J. Kamm ◽  
J.J. Burns
Keyword(s):  
Guinea Pig ◽  
Metabolic Activity ◽  
Animal Species ◽  
Adult Animal ◽  
Smooth Endoplasmic Reticulum ◽  
Fetal Life ◽  
Mixed Function Oxidase ◽  
Cytochrome P 450 ◽  
Microsomal Mixed Function Oxidase ◽  
Mixed Function Oxidase Activity

Unlike a variety of other animal species, such as the rabbit, mouse or rat, the guinea pig has a relatively long gestation period and is a more fully developed animal at birth. Kuenzig et al. reported that drug metabolic activity which increases very slowly during fetal life, increases rapidly after birth. Hepatocytes of a 3-day old neonate metabolize drugs and reduce cytochrome P-450 at a rate comparable to that observed in the adult animal. Moreover the administration of drugs like phenobarbital to pregnant guinea pigs increases the microsomal mixed function oxidase activity already in the fetus.Drug metabolic activity is, generally, localized within the smooth endoplasmic reticulum (SER) of the hepatocyte.

Glycogen in guinea pig neutrophils: Ultrastructural study of neutrophils at the intradermal site of BCG injection

1983 ◽  
Vol 41 ◽  
pp. 726-727
Author(s):  
Corazon D. Bucana
Keyword(s):  
Bone Marrow ◽  
Guinea Pig ◽  
Electron Density ◽  
Peritoneal Cavity ◽  
Ultrastructural Study ◽  
Guinea Pigs ◽  
Random Distribution ◽  
Glycogen Content ◽  
Polymorphonuclear Neutrophils ◽  
Ultrastructural Studies

In the circulating blood of man and guinea pigs, glycogen occurs primarily in polymorphonuclear neutrophils and platelets. The amount of glycogen in neutrophils increases with time after the cells leave the bone marrow, and the distribution of glycogen in neutrophils changes from an apparently random distribution to large clumps when these cells move out of the circulation to the site of inflammation in the peritoneal cavity. The objective of this study was to further investigate changes in glycogen content and distribution in neutrophils. I chose an intradermal site because it allows study of neutrophils at various stages of extravasation.Initially, osmium ferrocyanide and osmium ferricyanide were used to fix glycogen in the neutrophils for ultrastructural studies. My findings confirmed previous reports that showed that glycogen is well preserved by both these fixatives and that osmium ferricyanide protects glycogen from solubilization by uranyl acetate.I found that osmium ferrocyanide similarly protected glycogen. My studies showed, however, that the electron density of mitochondria and other cytoplasmic organelles was lower in samples fixed with osmium ferrocyanide than in samples fixed with osmium ferricyanide.

Ultrastructural Studies on Genital Infection with the Chlamydial Agent of Guinea Pig Inclusion Conjunctivitis

1977 ◽  
Vol 35 ◽  
pp. 352-353
Author(s):  
B. L. Soloff ◽  
A. L. Barron ◽  
H. J. White ◽  
R. G. Rank
Keyword(s):  
Guinea Pig ◽  
Sexual Contact ◽  
Chlamydia Psittaci ◽  
Genital Infection ◽  
Major Site ◽  
Ultrastructural Studies ◽  
Tissue Specimens ◽  
Guinea Pig Model ◽  
Adequate Tissue ◽  
Genital Tissue

Chlamydial organisms (specifically C. trachomatis) have been implicated as a frequent cause of genital infection in the human (1). Study of the histo- pathological aspects of such infections has been impeded because of difficulties in obtaining adequate tissue specimens and the lack of a suitable experimental host. In 1964, Murray (2) isolated the causative agent of guinea pig inclusion conjunctivitis which possesses similarities to human inclusion conjunctivitis. This guinea pig organism was found to be a member of the Chlamydia psittaci subgroup and was designated as the Gp-ic agent. Male guinea pigs have been successfully infected with Gp-ic by intraurethral inoculation. Transmission of the infection to the female by sexual contact has been demonstrated (3). We are not aware of any ultrastructural studies to date concerning the development of this agent in genital tissue.Studies in our laboratory have established that, in our guinea pig model, the cervix is the major site of injection.

Ultrastructural and chemical evidences of heterogeneity and hormone dependence of certain glycocalyces

1978 ◽  
Vol 36 (2) ◽  
pp. 322-323
Author(s):  
B. Monis ◽  
D. Lis ◽  
I. Parlanti ◽  
A. R. Eynard ◽  
M. A. Valentich ◽  
...  
Keyword(s):  
Guinea Pig ◽  
Concanavalin A ◽  
Ruthenium Red ◽  
Transitional Epithelium ◽  
Membrane Material ◽  
Hormone Dependence ◽  
Cellulose Acetate Electrophoresis ◽  
Electrophoretic Data ◽  
Fat Globule ◽  
Collecting Tubules

We are gathering evidences which indicate ultrastructural variations and chemical heterogeneity of certain glycocalyces as well as hormone dependence of some of them. Thus, in the lumenal glycocalyx of renal collecting tubules of the guinea-pig granular and filamentous structures were seen (1, fig. 1). By isolation, chemical analysis and cellulose acetate electrophoresis in various buffers of tubular membrane material, glycopeptides and glycosaminoglycans were identified (fig. 2).Guinea-pig and rat transitional epithelium of urinary tract showed a filamentous lumenal glycocalyx demonstrable with ruthenium red (fig. 3) but which only in part stained with concanavalin A. Chemical and electrophoretic data indicated that urothelium contains glycoproteins, glycosaminoglycans and glycolipids.The glycocalyx of the fat globule membrane of milk of several species has a granular appearance as shown by cationic dyes and by concanavalin A (2, 3, fig. 4 and 5). Also, several glycoproteins were isolated and identified on polyacrilamide gel electrophoresis (fig. 6). Glycosaminoglycans and certain glycolipids such as sulfatides were chemically identified in this glycocalyx.

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