Catecholamine Production Along the Nephron

Marco, Giovana Seno Di; Vio, Carlos P.; Santos, Oscar Fernando Pav Atilde O Dos; Schor, Nestor; Casarini, Dulce Elena

doi:10.1159/000110452

Cited by 11 publications

(11 citation statements)

References 21 publications

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“…The MAO and COMT enzymes are the main regulators of DA catabolism and are widely distributed in the renal cortex and the medulla [9]. The activity of both catabolic enzymes is high in renal tissue compared to that of peripheral organs, the mitochondrial enzyme MAO being the major metabolic pathway for biogenic amine degradation [9,32,33].…”

Section: Discussionmentioning

confidence: 99%

“…The activity of both catabolic enzymes is high in renal tissue compared to that of peripheral organs, the mitochondrial enzyme MAO being the major metabolic pathway for biogenic amine degradation [9,32,33]. COMT is abundantly expressed within the proximal tubular cells of the kidney and its inhibition significantly increased the DA content in the renal interstitial fluid as well as in urine [13,32,33].…”

Section: Discussionmentioning

confidence: 99%

“…The kidney has all the enzymatic machinery to synthesize and catabolize DA [9]. Renal DA is synthesized from neuronal and extraneuronal sources.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Angiotensin II on Renal Dopamine Metabolism: Synthesis, Release, Catabolism and Turnover

et al. 2010

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Background/Aims: Dopamine (DA) uptake inhibition in the renal cortex, elicited by angiotensin II (ANG II), is mediated by AT₁ receptors and signals through the phospholipase C pathway and activation of protein kinase C and CaM-kinase II. By this indirect way, ANG II stimulates renal Na⁺,K⁺-ATPase activity through DA intracellular reduction. In the present work, we continued to study different aspects of renal DA metabolism in DA-ANG II interaction, such as DA synthesis, release, catabolism and turnover. Methods: ANG II effects on DA synthesis, release, catabolism and turnover were measured in samples from the outer renal cortex of Sprague-Dawley rats. Results: ANG II reduced renal aromatic acid decarboxylate activity without affecting basal secretion of DA or its KCl-induced release. Moreover, ANG II enhanced monoamine oxidase activity without altering catechol-o-methyl transferase activity and increased DA turnover. Conclusion: Current results as well as previous findings show that ANG II modifies DA metabolism in rat renal cortex by reducing DA uptake, decreasing DA synthesis enzyme activity and increasing monoamine oxidase activity, and DA turnover. Together, all these effects may reduce DA accumulation into renal cells and decrease its endogenous content and availability. This would prevent D1 receptor recruitment and stimulation, while diminishing DA inhibition of Na⁺,K⁺-ATPase activity and stimulating sodium reabsorption.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Effects of Angiotensin II on Renal Dopamine Metabolism: Synthesis, Release, Catabolism and Turnover

et al. 2010

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“…Since cultured MC provide a convenient model for the study of renal synthesis and release of bioactive products, which could act as autocrine, intacrine and/or paracrine mediators [17][18][19], this cell line can be introduced as a suitable in vitro model in order to improve the knowledge of events related to regulation of the renal ACE2 levels and to further elucidate its role(s) in vivo as a target of treatment for kidney diseases.…”

Section: Introductionmentioning

confidence: 99%

Purification and characterization of angiotensin converting enzyme 2 (ACE2) from murine model of mesangial cell in culture

Aragão

Cunha

Arita

et al. 2011

International Journal of Biological Macromolecules

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Angiotensin converting enzyme 2 (ACE2) is a component of the renin-angiotensin system (RAS) which converts Ang II, a potent vasoconstrictor peptide into Ang 1-7, a vasodilator peptide which may act as a negative feedback hormone to the actions of Ang II. The discovery of this enzyme added a new level of complexity to this system. The mesangial cells (MC) have multiple functions in glomerular physiology and pathophysiology and are able to express all components of the RAS. Despite of being localized in these cells, ACE2 has not yet been purified or characterized. In this study ACE2 from mice immortalized MC (IMC) was purified by ion-exchange chromatography. The purified enzyme was identified as a single band around 60-70 kDa on SDS-polyacrylamide gel and by Western blotting using a specific antibody. The optima pH and chloride concentrations were 7.5 and 200 mM, respectively. The N-terminal sequence was homologous with many species ACE2 N-terminal sequences as described in the literature. ACE2 purified from IMC was able to hydrolyze Ang II into Ang 1-7 and the K(m) value for Ang II was determined to be 2.87 ± 0.76 μM. In conclusion, we purified and localized, for the first time, ACE2 in MC, which was able to generate Ang 1-7 from Ang II. Ang 1-7 production associated to Ang II degradation by ACE2 may exert a protective effect in the renal hemodynamic.

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“…TH is present in kidney tissue, where DDC is also highly expressed [17, 18]. Thus, the uptake of L-dopa by renal tubule cells from the ultrafiltrate or from the interstitial fluid provides the substrate for DA production.…”

Section: Introductionmentioning

confidence: 99%

L-Tyr-Induced Phosphorylation of Tyrosine Hydroxylase at Ser40: An Alternative Route for Dopamine Synthesis and Modulation of Na+/K+-ATPase in Kidney Cells

Taveira-da-Silva

Sampaio

Vieyra

et al. 2019

Kidney Blood Press Res

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Background/Aims: Dopamine (DA) is a natriuretic hormone that inhibits renal sodium reabsorption, being Angiotensin II (Ang II) its powerful counterpart. These two systems work together to maintain sodium homeostasis and consequently, the blood pressure (BP) within normal limits. We hypothesized that L-tyrosine (L-tyr) or L-dihydroxyphenylalanine (L-dopa) could inhibit the Na⁺/K⁺-ATPase activity. We also evaluated whether L-tyr treatment modulates Tyrosine Hydroxylase (TH). Methods: Experiments involved cultured LLCPK₁ cells treated with L-tyr or L-dopa for 30 minutes a 37°C. In experiments on the effect of Dopa Descarboxylase (DDC) inhibition, cells were pre incubated for 15 minutes with 3-Hydroxybenzylhydrazine dihydrochloride (HBH), and them L-dopa was added for 30 minutes. Na⁺/K⁺-ATPase activity was quantified colorimetrically. We used immunoblotting and immunocytochemistry to identify the enzymes TH, DDC and the dopamine receptor D₁R in LLCPK₁ cells. TH activity was accessed by immunoblotting (increase in the phosphorylation). TH and DDC activities were also evaluated by the modulation of the Na⁺/K⁺-ATPase activity, which can be ascribed to the synthesis of dopamine. Results: LLCPK₁ cells express the required machinery for DA synthesis: the enzymes TH, and (DDC) as well as its receptor D₁R, were detected in control steady state cells. Cells treated with L-tyr or L-dopa showed an inhibition of the basolateral Na⁺/K⁺-ATPase activity. We can assume that DA formed in the cytoplasm from L-tyr or L-dopa led to inhibition of the Na⁺/K⁺-ATPase activity compared to control. L-tyr treatment increases TH phosphorylation at Ser⁴⁰ by 100%. HBH, a specific DDC inhibitor; BCH, a LAT2 inhibitor; and Sch 23397, a specific D₁R antagonist, totally suppressed the inhibition of Na⁺/K⁺-ATPase activity due to L-dopa or L-tyr administration, as indicated in the figures. Conclusion: The results indicate that DA formed mainly from luminal L-tyr or L-dopa uptake by LAT2, can inhibit the Na⁺/K⁺-ATPase. In addition, our results showed for the very first time that TH activity is also significantly increased when the cells were exposed to L-tyr.

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Catecholamine Production Along the Nephron

Cited by 11 publications

References 21 publications

Effects of Angiotensin II on Renal Dopamine Metabolism: Synthesis, Release, Catabolism and Turnover

Effects of Angiotensin II on Renal Dopamine Metabolism: Synthesis, Release, Catabolism and Turnover

Purification and characterization of angiotensin converting enzyme 2 (ACE2) from murine model of mesangial cell in culture

L-Tyr-Induced Phosphorylation of Tyrosine Hydroxylase at Ser<sup>40</sup>: An Alternative Route for Dopamine Synthesis and Modulation of Na<sup>+</sup>/K<sup>+</sup>-ATPase in Kidney Cells

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