Prostaglandins and renin release in vitro

1981 ◽  
Vol 240 (6) ◽  
pp. E609-E614
Author(s):  
C. S. Lin ◽  
H. Iwao ◽  
S. Puttkammer ◽  
A. M. Michelakis
Keyword(s):  
Arachidonic Acid ◽  
Renal Cortex ◽  
The Other ◽  
Renin Release ◽  
Eicosatetraenoic Acid ◽  
Juxtaglomerular Cells ◽  
Prostaglandin F2 Alpha ◽  
Prostaglandin System

The present studies were undertaken to explore further the role of prostaglandins in the release of renin from the renal cortex. To provide the best assessment of renin release, renin was determined by a radioimmunoassay for the direct measurement of renin. Slices of mouse renal cortex were incubated at 37 degrees C with arachidonic acid (AA), 5,8,11,14-eicosatetraenoic acid (ETA), indomethacin, prostaglandins, and synthetic prostaglandin endoperoxide analogue (EPA). Our results showed that AA at 1.5 X 10(-8) M significantly increased renin release at 10 and 30 min of incubation. This renin increase ws abolished by either ETA or indomethacin. Prostaglandin F2 alpha (PGF2 alpha) also significantly stimulated renin release at 10 and 60 min. PGE2 and 16,16-dimethyl PGE2 (DMPGE2) showed much less renin release-stimulating activity. EPA and PGI2 on the other hand very strongly stimulated renin release. However, at higher concentrations the stimulating effect of PGI2 and EPA disappeared and even became inhibitory in the case of EPA. Other prostaglandins were found to have no effect on renin release. The results suggest that the prostaglandin system directly affects renin release from the juxtaglomerular cells independent of systemic neurogenic and hemodynamic influences.

Guanosine 3',5'-cyclic monophosphate as a mediator of inhibition of renin release

1988 ◽  
Vol 255 (3) ◽  
pp. F474-F478 ◽  
Author(s):  
W. L. Henrich ◽  
E. A. McAllister ◽  
P. B. Smith ◽  
W. B. Campbell
Keyword(s):  
Methylene Blue ◽  
Arachidonic Acid ◽  
Inhibitory Effect ◽  
Renin Release ◽  
Juxtaglomerular Cells ◽  
Cyclic Monophosphate ◽  
Direct Inhibitory Effect ◽  
Cortical Slices

The role of guanosine 3',5'-cyclic monophosphate (cGMP) as an inhibitory mediator of tissue renin release was examined in two different in vitro preparations. In rat superficial cortical slices, renin release stimulated by isoproterenol (10(-5) M) was ablated by atriopeptin III (ANP, 2.1 x 10(-8) M), nitroprusside (NP, 10(-3) M), and 8-bromoguanosine 3',5'-cyclic monophosphate (8-BrcGMP, 10(-3) and 10(-6) M). Arachidonic acid (10(-3) M)-stimulated renin release was also inhibited by ANP and 8-BrcGMP (10(-3) and 10(-6) M). Both ANP and NP increased tissue cGMP concentrations significantly (P less than 0.05), but neither had an effect on adenosine 3',5'-cyclic monophosphate (cAMP) concentrations. When methylene blue (10(-5) M), an inhibitor of guanylate cyclase, was added to slices incubated with isoproterenol and ANP, the inhibition of renin release by ANP was abolished. These results were confirmed in a preparation of isolated cultured rat juxtaglomerular cells. In these cells, isoproterenol induced a significant increase (58%, P less than 0.01) in renin release, which was inhibited by the addition of 8-BrcGMP (10(-6) M). These data demonstrate a direct inhibitory effect of ANP on isoproterenol- and arachidonic acid-induced renin release. The results with NP, 8-BrcGMP, and methylene blue suggest that cGMP is an intracellular mediator of this inhibition.

scholarly journals Prostacyclin as a potent effector of adipose-cell differentiation

1989 ◽  
Vol 257 (2) ◽  
pp. 399-405 ◽  
Author(s):  
R Négrel ◽  
D Gaillard ◽  
G Ailhaud
Keyword(s):  
Arachidonic Acid ◽  
Cyclic Amp ◽  
Critical Role ◽  
Terminal Differentiation ◽  
Prostaglandin F2 Alpha ◽  
Adipogenic Effect ◽  
Adipose Cells

The terminal differentiation of Ob1771 pre-adipose cells induced by arachidonic acid in serum-free hormone-supplemented medium containing insulin, transferrin, growth hormone, tri-iodothyronine and fetuin (5F medium) was strongly diminished in the presence of inhibitors of prostaglandin synthesis, namely aspirin or indomethacin. Carbaprostacyclin, a stable analogue of prostacyclin (prostaglandin I2) known to be synthesized by pre-adipocytes and adipocytes, behaved as an efficient activator of cyclic AMP production and was able, when added to 5F medium, to mimic the adipogenic effect of arachidonic acid. Prostaglandins E2, F2 alpha and D2, unable to affect the cyclic AMP production, failed to substitute for carbaprostacyclin. However, prostaglandin F2 alpha, which is another metabolite of arachidonic acid in pre-adipose and adipose cells, able to promote inositol phospholipid breakdown and protein kinase C activation, potentiated the adipogenic effect of carbaprostacyclin. In addition, carbaprostacyclin enhanced both a limited proliferation and terminal differentiation of adipose precursor cells isolated from rodent and human adipose tissues maintained in primary culture. These results demonstrate the critical role of prostacyclin and prostaglandin F2 alpha on adipose conversion in vitro and suggest a paracrine/autocrine role of both prostanoids in the development of adipose tissue in vivo.

scholarly journals Lipopolysaccharides prime whole human blood and isolated neutrophils for the increased synthesis of 5-lipoxygenase products by enhancing arachidonic acid availability: involvement of the CD14 antigen.

1993 ◽  
Vol 178 (4) ◽  
pp. 1347-1355 ◽  
Author(s):  
M E Surette ◽  
R Palmantier ◽  
J Gosselin ◽  
P Borgeat
Keyword(s):  
Arachidonic Acid ◽  
Mononuclear Cells ◽  
Leukotriene B4 ◽  
Eicosatetraenoic Acid ◽  
Tnf Alpha ◽  
Peripheral Blood Mononuclear ◽  
Necrosis Factor Alpha ◽  
Factor Alpha ◽  
Priming Activity

Stimulation of heparinized blood with 1 microM formyl-methionyl-leucyl-phenylalanine (FMLP) resulted in the formation of < 30 pmol/ml plasma of 5-lipoxygenase (5-LO) products. The preincubation of blood with 1 microgram/ml of lipopolysaccharide (LPS) (Escherichia coli 0111-B4) for 30 min before stimulation with FMLP resulted in the accumulation of 250-300 pmol of 5-LO products per ml plasma. The major products detected were leukotriene B4 and (5S)-hydroxy-6,8,11,14-eicosatetraenoic acid which were produced in equivalent amounts. The priming activity was detectable with as little as 1-10 ng LPS per ml blood and was optimal using 1-10 micrograms LPS/ml blood. The priming for 5-LO product synthesis was optimal after 20-30 min of preincubation with LPS and declined at preincubation times > 30 min. The priming effect of LPS was also observed using the complement fragment C5a or interleukin 8 as agonists. Polymorphonuclear leukocytes (PMN) and peripheral blood mononuclear cells accounted for 80 and 20% of the synthesis of 5-LO products, respectively. The ability of LPS to prime isolated PMN was dependent on the presence of plasma and was inhibited by the anti-CD14 antibody IOM2, indicating a CD14-dependent priming mechanism. The priming of whole blood with tumor necrosis factor alpha (TNF-alpha) and LPS was additive and the presence of mononuclear cells did not enhance the ability of LPS to prime PMN, indicating that the priming activity of LPS is independent of LPS-induced TNF-alpha synthesis. The mechanism by which LPS enhance 5-LO product synthesis in PMN was investigated. Treatment of PMN with LPS strongly enhanced the release of arachidonic acid after stimulation with FMLP. The release of arachidonic acid was optimal 2-3 min after stimulation with FMLP, attaining levels 5-15-fold greater than those observed in unprimed cells stimulated with FMLP. These results demonstrate that LPS dramatically increases the ability of blood to generate 5-LO products, and support the putative role of leukotrienes in pathological states involving LPS.

Abstract 4023: Aspirin “Resistance”: Role of Pre-existent Platelet Reactivity and Correlation Between Tests

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Andrew L Frelinger ◽  
Youfu Li ◽  
Matthew D Linden ◽  
Inge Tarnow ◽  
Marc R Barnard ◽  
...  
Keyword(s):  
Arachidonic Acid ◽  
Platelet Aggregation ◽  
Platelet Function ◽  
Normal Subjects ◽  
Aspirin Resistance ◽  
The Other ◽  
List Type ◽  
Platelet Function Test ◽  
Function Test

Background: Aspirin “resistance” (i.e. hyporesponsiveness to aspirin in a platelet function test) has been widely reported, but the underlying mechanism is unclear. We examined the role of pre-existent platelet hyperreactivity in aspirin “resistance”. We also determined the correlation between aspirin resistance defined by serum thromboxane (TX) B 2 (the most specific test of aspirin’s effect) and other assays of platelet function. Methods: Platelet function measured before and after aspirin 81 mg daily for 7 days was analyzed by Spearman’s rank correlation. Normal subjects (n=165) were studied because virtually all clinically relevant patients are already taking aspirin. An additional advantage of the use of normal subjects is that the platelet response to stimuli is not influenced (with resultant increased scatter of the data) by an underlying disease, e.g. coronary artery disease, which causes platelet hyperreactivity. Results: The proportion of the post-aspirin platelet function predicted by the pre-aspirin platelet function was 28.3 ± 7.5% (mean ± asymptotic standard error) for serum TXB 2 , 39.3 ± 6.8% for urinary 11-dehydro TXB 2 , 4.4 ± 7.7% for arachidonic acid-induced platelet aggregation, 40.4 ± 7.1% for ADP-induced platelet aggregation, 26.3 ± 9.2% for the VerifyNow Aspirin Assay®, and 45.0 ± 10.9% for the TEG® PlateletMapping ™ System with arachidonic acid. Spearman rank order correlations were highly significant for comparisons between assays when both pre-aspirin and post-aspirin results were included in the analysis. However, residual serum TXB 2 levels post-aspirin treatment were not significantly associated with post-treatment results of any of the other assays. Platelet count correlated with pre-aspirin serum TXB 2 and VerifyNow Aspirin Assay, but not with any post-aspirin platelet function test. Conclusions: Aspirin “resistance” (i.e. hyporesponsiveness to aspirin in a laboratory test) is in part unrelated to aspirin but is the result of underlying platelet hyperreactivity prior to the institution of aspirin therapy. Individuals identified as aspirin “resistant” defined by serum TXB 2 are not the same individuals identified by the other tests.

scholarly journals Incorporation of platelet and leukocyte lipoxygenase metabolites by cultured vascular cells

Blood ◽  
1986 ◽  
Vol 67 (2) ◽  
pp. 373-378 ◽  
Author(s):  
AI Schafer ◽  
H Takayama ◽  
S Farrell ◽  
MA Jr Gimbrone
Keyword(s):  
Endothelial Cells ◽  
Arachidonic Acid ◽  
Smooth Muscle ◽  
Fatty Acid ◽  
Smooth Muscle Cells ◽  
Vascular Function ◽  
Muscle Cells ◽  
Arachidonic Acid Metabolism ◽  
Eicosatetraenoic Acid

Abstract When arachidonic acid metabolism is studied during platelet-endothelial interactions in vitro, the predominant cyclooxygenase end products of each cell type (thromboxane B2 and 6-keto-prostaglandin-F1 alpha, respectively) are essentially completely recovered in the cell-free supernatants of these reactions. In contrast, 50% of 12-hydroxy- 5,8,10,14-eicosatetraenoic acid (12-HETE), the major lipoxygenase metabolite from platelets, is released into the cell-free supernatant. In investigating the basis of this observation, we have found that platelet lipoxygenase metabolites were generated to the same extent during these coincubations but became rapidly incorporated into the endothelial cells. The endothelial cell-associated 12-HETE was present not only as free fatty acid, but was also incorporated into cellular phospholipids and triglycerides. When purified 3H-12-HETE, 3H-5-HETE (the major hydroxy acid lipoxygenase product of leukocytes), and 3H- arachidonic acid (the common precursor of these metabolites) were individually incubated with suspensions of cultured bovine aortic endothelial cells or smooth muscle cells, different patterns of intracellular lipid distribution were found. In endothelial cells, 12- HETE was incorporated equally into phospholipids and triglycerides, whereas 5-HETE was incorporated preferentially into triglycerides, and arachidonic acid was incorporated into phospholipids. In smooth muscle cells, both 12-HETE and 5-HETE showed more extensive incorporation into triglycerides. The rapid and characteristic incorporation and esterification of platelet and leukocyte monohydroxy fatty acid lipoxygenase products by endothelial and smooth muscle cells suggests a possible physiologic role for these processes in regulating vascular function.

THE ROLE OF ADSORPTION IN CONTROLLING THE RATE OF REACTION OF CHLORAMBUCIL WITH PROTEIN

1963 ◽  
Vol 41 (4) ◽  
pp. 931-939 ◽  
Author(s):  
J. H. Linford
Keyword(s):  
Molecular Weight ◽  
Carboxylic Acid ◽  
Bovine Serum Albumin ◽  
Inverse Relationship ◽  
Reaction Rate ◽  
The Other ◽  
Alkylation Reaction ◽  
Rate Of Reaction

Two proteins, haemoglobin and bovine serum albumin, have been studied with respect to their rates of alkylation by chlorambucil in vitro at 37 °C and pH 8.4. The proteins are of nearly the same molecular weight and free carboxylic acid content, but the alkylation reaction is 30 times faster with haemoglobin. On the other hand, the adsorption of chlorambucil by albumin is 20 times greater than that exhibited by haemoglobin. This inverse relationship between extent of adsorption and reaction rate suggests that adsorption protects the chlorambucil from activation in the solvent.

Lack of effect of cholinergic agents or endogenous guanosine 3':5'-monophosphate on renin release by slices of rat renal cortex in vitro

1980 ◽  
Vol 29 (13) ◽  
pp. 1933-1937
Author(s):  
Steven B. Leichter ◽  
Theodore A. Kotchen ◽  
W.Allen Rader ◽  
Jerry Rader
Keyword(s):  
Renal Cortex ◽  
Renin Release ◽  
Cholinergic Agents

Anionic and cationic exchange mechanisms in the skin of anurans, with special reference to Leptodactylidae in vivo

1971 ◽  
Vol 262 (842) ◽  
pp. 163-174 ◽  
Keyword(s):  
Transport Mechanism ◽  
Selective Inhibition ◽  
The Other ◽  
Sodium Absorption ◽  
Experimental Conditions ◽  
Net Flux ◽  
Cationic Exchange

In several species of anurans, the in vivo skin has been shown to absorb Na + and Cl - independently from dilute external solutions. That the mechanism for sodium absorption is different from that of chloride absroption is born out by the following: (1) Either of these ions is absorbed without an accompanying ion when this latter is impermeant. (2) From NaCl solutions there can be an unequal absorption of sodium and chloride. (3) A selective inhibition of the absorption of one of the ions can be produced experimentally, while the net flux of the other remains unchanged. In all these situations, the absorbed ion has to be exchanged against an endogenous ion of the same charge. In Calyptocephalella gayi , H + and HCO - 3 are exchanged against sodium and chloride respectively. A comparison of the relationships between H + excretion and Na + absorption in vivo skins and shortcircuited in vitro skins shows that in the latter no H + excretion occurs, only the Na + transport being maintained under these experimental conditions. From this, one must conclude that the active Na + transport is the motive factor of the transport mechanism. H + excretion by the in vivo skin plays the role of physiologically short-circuiting the Na + transport.

scholarly journals Glucomannan-Mediated Attachment of Rhizobium leguminosarum to Pea Root Hairs Is Required for Competitive Nodule Infection

2008 ◽  
Vol 190 (13) ◽  
pp. 4706-4715 ◽  
Author(s):  
Alan Williams ◽  
Adam Wilkinson ◽  
Martin Krehenbrink ◽  
Daniela M. Russo ◽  
Angeles Zorreguieta ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Rhizobium Leguminosarum ◽  
Root Hairs ◽  
The Other ◽  
Plant Interactions ◽  
Wild Type ◽  
Polysaccharide Synthesis ◽  
Surface Polysaccharides

ABSTRACT The Rhizobium leguminosarum biovar viciae genome contains several genes predicted to determine surface polysaccharides. Mutants predicted to affect the initial steps of polysaccharide synthesis were identified and characterized. In addition to the known cellulose (cel) and acidic exopolysaccharide (EPS) (pss) genes, we mutated three other loci; one of these loci (gmsA) determines glucomannan synthesis and one (gelA) determines a gel-forming polysaccharide, but the role of the other locus (an exoY-like gene) was not identified. Mutants were tested for attachment and biofilm formation in vitro and on root hairs; the mutant lacking the EPS was defective for both of these characteristics, but mutation of gelA or the exoY-like gene had no effect on either type of attachment. The cellulose (celA) mutant attached and formed normal biofilms in vitro, but it did not form a biofilm on root hairs, although attachment did occur. The cellulose-dependent biofilm on root hairs appears not to be critical for nodulation, because the celA mutant competed with the wild-type for nodule infection. The glucomannan (gmsA) mutant attached and formed normal biofilms in vitro, but it was defective for attachment and biofilm formation on root hairs. Although this mutant formed nodules on peas, it was very strongly outcompeted by the wild type in mixed inoculations, showing that glucomannan is critical for competitive nodulation. The polysaccharide synthesis genes around gmsA are highly conserved among other rhizobia and agrobacteria but are absent from closely related bacteria (such as Brucella spp.) that are not normally plant associated, suggesting that these genes may play a wide role in bacterium-plant interactions.

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