Amino acids induce renal vasodilatation in isolated perfused kidney: coupling to oxidative metabolism

1984 ◽  
Vol 247 (6) ◽  
pp. H999-H1004 ◽  
Author(s):  
M. Brezis ◽  
P. Silva ◽  
F. H. Epstein
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Rat Kidney ◽  
O2 Consumption ◽  
Metabolic Substrates ◽  
Parallel Increase ◽  
Protein Feeding ◽  
Amino Acid Analogues ◽  
Renal Vascular ◽  
Dose Dependent

Renal vasodilatation regularly accompanies protein feeding and amino acid infusions, but the mechanism is unknown. The effects of several different amino acids on renal hemodynamics were studied in the isolated rat kidney, perfused with glucose as the only other substrate. Addition of amino acids produced a dose-dependent, brisk, and sustained decrease in renal vascular resistance (by 5–35%) without change in glomerular filtration rate (GFR). The vasodilatation was associated with a parallel increase in O2 consumption (increases QO2). The effect was most marked with amino acids actively metabolized by the kidney, such as glutamine (at 2 mM), but was seen with most amino acids at 8 mM. The amino acid analogues alpha-aminobutyrate, taurine, and cycloleucine, cotransported with sodium but not metabolized, did not cause significant vasodilatation or increases QO2. Blocking active transport with ouabain blunted the amino acid-induced vasodilatation and increases QO2. Similar resistance to amino acids was produced by halting GFR with hyperoncotic medium. Restoration of GFR by increasing perfusion pressure in the presence of hyperoncotic medium reestablished amino acid-induced vasodilatation and increases QO2. Furosemide did not block the vasodilatory response. Inhibition of mitochondrial respiration by antimycin blocked both vasodilatation and increases QO2, but rotenone blockade could be bypassed by succinate or glutamine. Amino acids have a direct vasodilating action on isolated kidneys probably related to their role as metabolic substrates and linked to an increase in renal O2 consumption.

COMPETITION BETWEEN AMINO ACIDS FOR TRANSPORT INTO EHRLICH ASCITES CARCINOMA CELLS

1961 ◽  
Vol 39 (11) ◽  
pp. 1717-1735 ◽  
Author(s):  
P. G. Scholefield
Keyword(s):  
Carbon Dioxide ◽  
Amino Acids ◽  
Amino Acid ◽  
Ehrlich Ascites Carcinoma ◽  
Carcinoma Cells ◽  
Transport Systems ◽  
Radioactive Carbon ◽  
Ehrlich Ascites ◽  
Competitive Inhibitors ◽  
Amino Acid Analogues

The cumulative entry of amino acids into Ehrlich ascites carcinoma cells is due to the presence of active transport systems, each with its own specific range of substrates. Several amino acids and amino acid analogues may have an affinity for the same transport system and thus may inhibit transport of other amino acids by acting as competitive inhibitors or competitive substrates. Loss of methionine from ascites cells takes place by a diffusion process which obeys Fick's law. Leucine accumulation by ascites cells is small and is increased on addition of certain other amino acids. The increase is not due to inhibition of leucine oxidation as increase in the rate of production of radioactive carbon dioxide from labeled leucine also occurs. Kinetic aspects of these results are discussed.

Effect of a Leucine Analogue on Incorporation of Glycine into the Proteins of Explanted Chick Embryos

Development ◽  
1958 ◽  
Vol 6 (2) ◽  
pp. 262-269
Author(s):  
Phyllis W. Schultz ◽  
Heinz Herrmann
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Chick Embryo ◽  
Total Protein ◽  
Nutrient Medium ◽  
Chick Embryos ◽  
Agar Gel ◽  
Egg Extract ◽  
Amino Acid Analogues

Amino acid analogues have been observed to give rise to abnormal forms of development of chick and amphibian embryos (Herrmann, 1953; Rothfels, 1954; Waddington & Sirlin, 1954; Feldman & Waddington, 1955; Herrmann, Rothfels-Konigsberg, & Curry, 1955). Assuming that these disturbances may be due to interference with the utilization of amino acids for protein formation, we have attempted an analysis of this effect by comparison of the protein contents and of the uptake of glycine into the proteins of chick embryo explants in the presence and absence of amino acid analogues. The results of such experiments are reported in this paper. The chick embryos used for explanation, the explantation technique, and the determination of total protein glycine and of tracer glycine were essentially the same as described previously (Herrmann & Schultz, 1958). The embryos were explanted at the 11–13 somite stage on to the surface of an agar gel containing egg extract as nutrient medium following the procedure given by Spratt (1947) as modified by Rothfels (1954).

Opiate nerves mediate feline pyloric response to intraduodenal amino acids

1985 ◽  
Vol 248 (3) ◽  
pp. G307-G312 ◽  
Author(s):  
J. C. Reynolds ◽  
A. Ouyang ◽  
S. Cohen
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Spike Activity ◽  
Saline Control ◽  
Myoelectric Activity ◽  
Neural Pathways ◽  
Acid Solutions ◽  
Cervical Vagotomy ◽  
Amino Acid Solutions ◽  
Dose Dependent

Intraluminal pressures and myoelectric activity were recorded from the feline antrum, pylorus, and duodenum in response to intraduodenal amino acid solutions. Mixed amino acids (0.02 mg/ml, 3.0 ml) increased the amplitude of pyloric contractions (59.7 +/- 7.9 mmHg) and pyloric spike activity (73.7 +/- 6.8% of slow waves with spike activity) compared with a saline control (P less than 0.001). The selectivity of these responses was determined with specific amino acids. L-Tryptophan (10 or 40 mM) produced a response similar to the mixed amino acid response, while L-phenylalanine or L-glycine (10 or 40 mM) had no effect. Intra-arterial tetrodotoxin, intraluminal ethyl aminobenzoate, or intravenous naloxone (1.0 mg/kg) abolished the pyloric responses to amino acids (P less than 0.02). Bilateral cervical vagotomy had no effect. Cholecystokinin octapeptide (CCK-OP) produced dose-dependent increases in the amplitude of pyloric contractions and in pyloric spike activity. The ED50 dose of CCK-OP (1.0 microgram/kg iv) gave an increase in pyloric pressure of 155.6 +/- 49.9 mmHg and in spike activity of 77.7 +/- 9.4%, similar to mixed amino acids or tryptophan. These effects of CCK-OP were not antagonized, however, by a dose of naloxone (1.0 mg/kg) that blocked the maximal pyloric response to leucine-enkephalin. We concluded intraduodenal mixed amino acids or tryptophan increase phasic, spike-dependent pyloric contractions in the cat via nonvagal, naloxone-sensitive neural pathways, phenylalanine, a structurally similar essential amino acid, had no effect on the feline gastroduodenal junction, and the pyloric responses to exogenous CCK-OP are mediated by pathways distinct from the responses to tryptophan or mixed amino acids.

Chelating polymers. I. The synthesis and acid dissociation behavior of several N-(p-vinylbenzenesulfonyl)-substituted diaminopolyacetic acid monomers, monomeric analogues, and related intermediates

1970 ◽  
Vol 48 (1) ◽  
pp. 163-175 ◽  
Author(s):  
R. M. Genik-Sas-Berezowsky ◽  
I. H. Spinner
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Dissociation Constants ◽  
Acid Dissociation ◽  
Inductive Effects ◽  
Cyclic Amide ◽  
Amino Acid Analogues ◽  
Related Compounds ◽  
Chelating Polymers ◽  
Made In

Two new chelating monomers, N-(p-vinylbenzenesulfonyl)1,2-diaminoethane-N′,N′-diacetic (SS-EDDA) and -N,N′,N′-triacetic (SS-ED3A) acids, as well as several monomeric analogues and related intermediates have been prepared. In addition, 2-oxo-1-piperazine acetic (S-KP), 3-oxo-1-piperazine acetic (U-KP), and 2-oxo-1,4-piperazine diacetic (3-KP) acids have been synthesized and the interconvertibility between these cyclic amides and their unsubstituted linear amino acid analogues, ethylene-diamine-N,N′-diacetic (S-EDDA), -N,N-diacetic (U-EDDA), and -N,N,N′-triacetic (ED3A) acids respectively, was demonstrated.The acid dissociation constants of the various amino acids were determined potentiometrically at 25° and μ = 0.1 M(KNO3) and the results were compared with the hydrogen ion affinities of related compounds. Dissociation schemes were proposed for all the compounds based on these results. Rationalizations of the linear amino acid and the cyclic amide dissociation constants were made in terms of the effects of cyclization and the inductive effects of neighboring groups. These rationalizations were found to be helpful in clarifying the dissociation schemes previously proposed for several of the linear amino acids.

Amino acids suppress proteolysis independent of insulin throughout the neonatal period

1997 ◽  
Vol 272 (4) ◽  
pp. E592-E599 ◽  
Author(s):  
B. B. Poindexter ◽  
C. A. Karn ◽  
J. A. Ahlrichs ◽  
J. Wang ◽  
C. A. Leitch ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Neonatal Period ◽  
Essential Amino Acids ◽  
Whole Body ◽  
Amino Acid Availability ◽  
Dose Dependent Fashion ◽  
Term Newborns ◽  
Dose Dependent ◽  
Acid Administration

To determine how increased amino acid availability alters rates of whole body proteolysis and the irreversible catabolism of the essential amino acids leucine and phenylalanine throughout the neonatal period, leucine and phenylalanine kinetics were measured under basal conditions and in response to intravenous amino acids in two separate groups of healthy, full-term newborns (at 3 days and 3 wk of age). The endogenous rates of appearance of leucine and phenylalanine (reflecting proteolysis) were suppressed equally in both groups and in a dose-dependent fashion (by approximately 10% with 1.2 g x kg(-1) x day(-1) and by approximately 20% with 2.4 g x kg(-1) x day(-1)) in response to intravenous amino acid delivery. Insulin concentrations remained unchanged from basal values during amino acid administration. The irreversible catabolism of leucine and phenylalanine increased in a stepwise fashion in response to intravenous amino acids; again, no differences were observed between the two groups. This study clearly demonstrates that the capacity to acutely increase rates of leucine oxidation and phenylalanine hydroxylation is fully present early in the neonatal period in normal newborns. Furthermore, these data suggest that amino acid availability is a primary regulator of proteolysis in normal newborns throughout the neonatal period.

Localization of the high-affinity glutamate transporter EAAC1 in rat kidney

1997 ◽  
Vol 273 (6) ◽  
pp. F1023-F1029 ◽  
Author(s):  
Chairat Shayakul ◽  
Yoshikatsu Kanai ◽  
Wen-Sen Lee ◽  
Dennis Brown ◽  
Jeffrey D. Rothstein ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Rat Kidney ◽  
Cell Volume Regulation ◽  
Glutamate Transporter ◽  
Transport Systems ◽  
Kidney Cortex ◽  
Acid Base Balance ◽  
Western Blots ◽  
High Affinity

Most amino acids filtered by the glomerulus are reabsorbed in the kidney via specialized transport systems. Recently, the cDNA encoding a high-affinity glutamate transporter, EAAC1, has been isolated and shown to be expressed at high levels in the kidney. To determine the potential role of EAAC1 in renal acidic amino acid reabsorption, the distribution of EAAC1 mRNA and protein in rat kidney was examined. In situ hybridization revealed that EAAC1 mRNA is expressed predominantly in S2 and S3 segments of the proximal tubules and at low levels in the inner stripe of outer medulla and inner medulla. Polyclonal antibodies raised against the carboxy terminus of EAAC1 recognized a single band of ∼70 kDa on Western blots of membrane protein from kidney cortex and medulla. Immunofluorescence microscopy revealed intense signals in the luminal membrane of S2 and S3 segments and weaker signals in S1 segments, descending thin limbs of long-loop nephrons, medullary thick ascending limbs, and distal convoluted tubules. These results are consistent with EAAC1 encoding the previously described apical high-affinity glutamate transporter in the kidney that mediates reabsorption of acidic amino acids in tubules beyond early proximal tubule S1 segments. Potential additional roles of EAAC1 in acid/base balance, cell volume regulation, and amino acid metabolism are discussed.

scholarly journals The mutagenicity of amino acid analogues inCoprinus lagopus

1974 ◽  
Vol 23 (1) ◽  
pp. 47-61 ◽  
Author(s):  
Philippa J. Talmud ◽  
D. Lewis
Keyword(s):  
Amino Acid ◽  
Mutation Frequency ◽  
Spontaneous Mutation ◽  
Base Change ◽  
Response Curves ◽  
Amino Acid Analogues ◽  
Single Base Change ◽  
Protein Incorporation ◽  
Dose Dependent ◽  
Spontaneous Mutation Frequency

SummaryThe amino acid analoguesp-fluorophenylalanine (PFP) and ethionine (ETH) are strongly mutagenic inCoprinus lagopus. The most pronounced effect was found with suppressor mutations of themet-1locus. PFP, at a concentration of 2·4 × 10−4M, increased the mutation frequency 500 fold and ETH, at a concentration of 2·4 × 10−3M, 30 fold over the spontaneous mutation frequency. From the spectrum of suppressors of themet-1locus and the dominant revertants of thead-82locus, induced by analogue treatments, it was concluded that both analogues induce single base-change mutations. The dose response curves follow a sigmoid plot, revealing that within a certain range of analogue concentrations, muta-genesis is strongly dose dependent.Using analogue resistant mutants, it has been shown that PFP mutagenesis is a function of its incorporation into protein. However, ETH mutagenesis is independent of protein incorporation but can be correlated with the degree of ethylation of nucleic acids. The synergistic effect PFP and ETH supports the evidence of the different mutagenic actions of the two analogues.

Food Intake, Growth and Tissue Amino Acids in Rats Fed Amino Acid Analogues

1985 ◽  
Vol 115 (9) ◽  
pp. 1180-1195 ◽  
Author(s):  
Jean K. Tews ◽  
Alfred E. Harper
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Food Intake ◽  
Amino Acid Analogues

Reciprocal renal effects of dopamine and 5-hydroxytryptamine formed within the rat kidney

1988 ◽  
Vol 75 (5) ◽  
pp. 503-507 ◽  
Author(s):  
Harold D. Itskovitz ◽  
Yih-Huey Chen ◽  
Charles T. Stier
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Renal Tubule ◽  
Competitive Inhibition ◽  
Rat Kidney ◽  
Acid Decarboxylase ◽  
Water Excretion ◽  
Amino Acid Decarboxylase ◽  
Before And After ◽  
Renal Dopamine

1. Clearance of inulin and p-aminohippurate and excretion of water and sodium were measured for eight to 11 clearance periods of 20 min duration in anaesthetized, 3% volume-expanded rats, before and after intravenous infusions of the amino acids l-dopa (l-3,4-dihydroxyphenylalanine) and 5-hydroxytryptophan. During the final two clearance periods, the peripheral decarboxylase inhibitor, carbidopa (S-α-hydrazino-3,4-dihydroxy-α-methylbenzenepropanoic acid monohydrate), was infused additionally. 2. Renal formation of dopamine (3,4-dihydroxyphenethylamine) and 5-hydroxytryptamine was demonstrated during infusions of l-dopa and 5-hydroxytryptophan, respectively; carbidopa blocked the renal formation of these biogenic amines. 3. During infusion of dopa, a diuresis and a natriuresis were observed; during the infusion of 5-hydroxytryptophan, slight reductions in clearances of inulin and p-aminohippurate, but significant reductions in sodium and water excretion, were measured. 4. The addition of carbidopa diminished diuretic and natriuretic responses to dopa as renal dopamine excretion decreased; the infusion of carbidopa also ameliorated the antinatriuretic and antidiuretic effects of 5-hydroxytryptophan, as 5-hydroxytryptamine excretion decreased. 5. Although dopa and 5-hydroxytryptophan are substrates for the same enzyme, aromatic l-amino-acid decarboxylase, simultaneous infusions of both amino acids at comparable rates gave no evidence of competitive inhibition of amine synthesis. However, the infusion of dopa, after 5-hydroxytryptophan, decreased its antinatriuretic and antidiuretic effects. 6. These data raise the possibility that dopamine and 5-hydroxytryptamine are formed as reciprocal intrarenal hormones by the identical enzyme, aromatic l-amino-acid decarboxylase, which is located within cells of the renal tubule.

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