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Acute infusion of angiotensin II regulates organic cation transporters function in the kidney: its impact on the renal dopaminergic system and sodium excretion
Fernandez, Belisario Enrique; Choi, Marcelo Roberto

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Título:	Acute infusion of angiotensin II regulates organic cation transporters function in the kidney: its impact on the renal dopaminergic system and sodium excretion
Autor(es):	Fernandez, Belisario Enrique; Choi, Marcelo Roberto
Descripción:	Fil: Fernandez, Belisario Enrique. Instituto Universitario de Ciencias de la Salud – Fundación Barceló. Secretaria de Ciencia y Tecnologia; Argentina.
Resumen:	A close relationship between angiotensin II (ANG II) and the renal dopaminergic system (RDS) has been reported. Our aim was to study whether renal dopamine and ANG II can interact to modify renal sodium handling and then to elucidate the related mechanism. Anesthetized male Sprague–Dawley rats were used in experiments. ANG II, exogenous dopamine, and decynium-22 (or D-22, an isocyanine that specifically blocks electrogenic organic cation transporters, OCTs), were infused in vivo for 120 min. We analyzed renal and hemodynamic parameters, renal Na+, K+-ATPase levels, OCT activity, and urinary dopamine concentrations. We also evaluated the expression of D1 receptor, electroneutral organic cation transporters (OCTNs), and OCTs. ANG II decreased renal excretion of sodium in the presence of exogenous dopamine, increased Na+, K+-ATPase activity, and decreased the urinary dopamine concentration. D-22 treatment exacerbated the ANG II-mediated decrease in renal excretion of sodium and dopamine urine excretion but did not modify ANG II stimulation of Na+, K+- ATPase activity. The infusion of ANG II did not affect the expression of D1 receptor, OCTs, or OCTNs. However, the activity of OCTs was diminished by the presence of ANG II. Although ANG II did not alter the expression of D1 receptor, OCTs, and OCTNs in renal tissues, it modified the activity of OCTs and thereby decreased the urinary dopamine concentration, showing a novel mechanism by which ANG II decreases dopamine transport and its availability in the tubular lumen to stimulate D1 receptor. This study demonstrates a relationship between ANG II and dopamine, where both agents counteract their effects on sodium excretion.
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Fecha:	2020-10-27
Formato:	application/pdf
Extensión:	13 paginas
Idioma:	eng
Lugar:	7006287, Buenos Aires (inhabited place)
Sede:	Buenos Aires
Carrera:	MEDICINA
Notas:	Trabajo de investigación publicado

Losartan prevents the imbalance between renal dopaminergic and renin angiotensin systems induced by fructose overload. L-Dopa/dopamine index as new potential biomarker of renal dysfunction
Fernandez, Belisario Enrique; Choi, Marcelo Roberto

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Título:	Losartan prevents the imbalance between renal dopaminergic and renin angiotensin systems induced by fructose overload. L-Dopa/dopamine index as new potential biomarker of renal dysfunction
Autor(es):	Fernandez, Belisario Enrique; Choi, Marcelo Roberto
Descripción:	Fil: Fernandez, Belisario Enrique. Instituto Universitario de Ciencias de la Salud – Fundación Barceló. Secretaria de Ciencia y Tecnologia; Argentina.
Resumen:	Background: The renin angiotensin system (RAS) and the renal dopaminergic system (RDS) act as autocrine and paracrine systems to regulate renal sodium management and inflammation and their alterations have been associated to hypertension and renal damage.Nearly 30–50% of hypertensive patients have insulin resistance (IR),with a strong correlation between hyperinsulinemia and microalbuminuria. Objective: The aimof this studywas to demonstrate the existence of an imbalance between RAS and RDS associated to IR, hypertension and kidney damage induced by fructose overload (FO), aswell as to establish their prevention, by pharmacological inhibition of RAS with losartan. Materials/Methods: Ninety-six male Sprague-Dawley ratswere randomly divided into four groups and studied at 4, 8 and 12 weeks: control group (C4, C8 and C12; tap water to drink); fructose-overloaded group (F4, F8 and F12; 10% w/v fructose solution to drink); losartan-treated control (L) group (L4, L8 and L12; losartan 30 mg/kg/day, in drinkingwater); and fructose-overloaded plus losartan group (F+L4, F+L8 and F+L12, in fructose solution). Results: FO inducedmetabolic and hemodynamic alterations as well as an imbalance between RAS and RDS, characterized by increased renal angiotensin II levels and AT1R overexpression, reduced urinary excretion of dopamine, increased excretion of L-dopa (increased L-dopa/dopamine index) and down-regulation of D1R andtubulardopamine transporters OCT-2, OCT-N1 and total OCTNs. This imbalance was accompanied by an overexpression of renal tubular Na+, K+-ATPase, pro-inflammatory (NF-kB, TNF-α, IL-6) and pro-fibrotic (TGF-β1 and collagen) markers and by renal damage (microalbuminuria and reduced nephrin expression). Losartan prevented the metabolic and hemodynamic alterations induced by FO from week 4. Increased urinary L-dopa/dopamine index and decreased D1R renal expression associated to FO were also prevented by losartan since week 4. The same pattern was observed for renal expression of OCTs/OCTNs, Na+, K+-ATPase, pro-inflammatory and pro-fibroticmarkers from week 8. The appearance of microalbuminuria and reduced nephrin expression was prevented by losartan at week 12. Conclusion: The results of this study provide new insight regarding the mechanisms by which a pro-hypertensive and pro-inflammatory system, such as RAS, downregulates another anti-hypertensive and anti-inflammatory system such as RDS. Additionally, we propose the use of L-dopa/dopamine index as a biochemical marker of renal dysfunction in conditions characterized by sodiumretention, IR and/or hypertension, and as a predictor of response to treatment and follow-up of these processes.
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Contribuidores:	Rukavina Mikusic, Natalia Lucia; Kouyoundzuan, Nicolas Martin; Uceda, Ana; Del Mauro, Julieta Sofia; Pandolfo, Marcela; Gironacci, Mariela Mercedes; Puyo, Ana Maria; Toblli, Jorge Eduardo
Fecha:	2020-02-04
Formato:	application/pdf
Extensión:	15 paginas
Idioma:	eng
Lugar:	7006287, Buenos Aires (inhabited place)
Sede:	Buenos Aires
Carrera:	MEDICINA
Notas:	Trabajo de investigación publicado

Participación del sistema dopaminérgico renal en fisiopatogenia de la hipertensión arterial y el daño renal en un modelo experimental de síndrome metabólico.
Choi, Marcelo Roberto

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