The Experts below are selected from a list of 153 Experts worldwide ranked by ideXlab platform
E A Francischetti - One of the best experts on this subject based on the ideXlab platform.
-
Effects of long-term administration of isradipine on renal hemodynamics and Sodium Metabolism.
Journal of cardiovascular pharmacology, 1992Co-Authors: E A Francischetti, I Barroso, A Da Silva, V G FagundesAbstract:The objective of this double-blind, placebo-controlled study was to evaluate the effects of isradipine on renal hemodynamics and function. Ten patients with mild-to-moderate hypertension were given isradipine at 2.5 mg twice daily for 3 months after 4 weeks of placebo washout. Renal studies were performed 2 h after the morning administration of treatment. The results of these evaluations indicate that isradipine as monotherapy significantly reduced the mean arterial pressure, while the effective renal plasma flow was increased (+16%) and glomerular filtration rate remained virtually unchanged (-8.7 ml/min). The filtration fraction and renal vascular resistance decreased significantly. There was a significant decrease in the absolute rate of proximal Sodium reabsorption, and a significant increase in the distal reabsorption. Clearance of Sodium remained unchanged. In conclusion, monotherapy with low-dose isradipine was not only effective in controlling blood pressure, but also decreased the renal vascular resistance while avoiding glomerular hyperfiltration, and exerted a protective effect on renal hemodynamics. Natriuresis also remained stable despite the blood pressure reduction.
-
Effects of long-term administration of isradipine on renal hemodynamics and Sodium Metabolism
Journal of Cardiovascular Pharmacology, 1992Co-Authors: E A Francischetti, Barroso I, Da Silva AAbstract:The objective of this double-blind, placebo-controlled study was to evaluate the effects of isradipine on renal hemodynamics and function. Ten patients with mild-to-moderate hypertension were given isradipine at 2.5 mg twice daily for 3 months after 4 weeks of placebo washout. Renal studies were performed 2 h after the morning administration treatment. The results of these evaluations indicate that isradipine as monotherapy significantly reduced the mean arterial pressure, while the effective renal plasma flow was increased (+16%) and glomerular filtration rate remained virtually unchanged (−8.7 ml/min)
Anita Aperia - One of the best experts on this subject based on the ideXlab platform.
-
Increased blood pressure and loss of anp-induced natriuresis in mice lacking DARPP-32 gene.
Clinical and experimental hypertension (New York N.Y. : 1993), 2001Co-Authors: Ann-christine Eklöf, Ulla Holtbäck, Paul Greengard, J. Svennilson, Allen A. Fienberg, Anita AperiaAbstract:Atrial natriuretic peptide (ANP) is an important regulator of Sodium Metabolism and indirectly of blood pressure. Evidence has accumulated that ANP regulates Sodium Metabolism through a cascade of steps involving an increase in the level of cGMP, activation of cGMP-dependent protein kinase (PKG), and inhibition of renal tubular Na+,K+ -ATPase activity.One of the major substrates for PKG is DARPP-32. In the present study we observed that ANP does not induce natriuresis in mice that lack DARPP- 32. In contrast, there was a 4-fold increase in urinary Sodium excretion following ANP administration to wild type mice. ANP as well as Zaprinast, a selective inhibitor of cGMP phosophodiesterase, inhibited renal Na+,K+-ATPase activity in wild type mice but had no such effect in mice lacking DARPP-32. Mean arterial blood pressure, measured in conscious animals, was significantly increased in DARPP-32 deficient mice as compared to wild type mice.The results confirm that DARPP-32 acts as a third messenger in the ANP si...
-
Dopamine-induced translocation of protein kinase C isoforms visualized in renal epithelial cells.
American journal of physiology. Cell physiology, 2000Co-Authors: Susana Nowicki, Hjalmar Brismar, María Sol Kruse, Anita AperiaAbstract:Short-term regulation of Sodium Metabolism is dependent on the modulation of the activity of Sodium transporters by first and second messengers. In understanding diseases associated with Sodium ret...
-
Mechanisms by which intrarenal dopamine and ANP interact to regulate Sodium Metabolism.
Clinical and experimental hypertension (New York N.Y. : 1993), 2000Co-Authors: Hjalmar Brismar, Ulla Holtbäck, Anita AperiaAbstract:Maintenance of a normal blood pressure requires a precise and fine-tuned regulation of salt Metabolism. This is accomplished by a bidirectional regulation of renal tubular Sodium transporters by natriuretic and antinatriuretic hormones. Dopamine, produced in the renal proximal tubular cells, plays an important role in this interactive system. Dopamine inhibits the activity of Na+,K+ATPase as well as of many important Sodium influx pathways in the nephron. These effects of dopamine are particularly pronounced in situation of Sodium loading.There is an abundance of evidence suggesting that the natriuretic effects of ANP are to a large extent mediated via renal dopamine 1 like receptors. The renal tubular dopamine 1 like receptors are, under basal conditions, mainly located intracellularly. ANP and its second messenger, cGMP, cause a rapid translocation of the dopamine 1 like receptors to the plasma membrane. This phenomenon may explain how ANP and dopamine act in concert to regulate Sodium Metabolism. Regul...
-
intrarenal dopamine a key signal in the interactive regulation of Sodium Metabolism
Annual Review of Physiology, 2000Co-Authors: Anita AperiaAbstract:The kidney regulates Sodium Metabolism with extraordinary precision and sensitivity. This is accomplished by an intricate interaction between signals from extrarenal and intrarenal sources and between anti-natriuretic and natriuretic factors. Dopamine, produced in renal proximal tubule cells, plays a central role in this interactive network. Natriuretic hormones that are released from extrarenal sources, such as atrial natriuretic peptide, mediate some of their effects via renal dopamine receptors. On the level of the tubules, dopamine acts by opposing the effects of anti-natriuretic factors, such as angiotensin II and alpha-adrenergic receptors. Sodium retention leads to an increase in renal dopamine tonus, and the natriuretic effects of dopamine are more prominent under this condition. Inhibition or down-regulation of dopamine receptors significantly attenuates the natriuretic response to salt loading. Renal dopamine is modulated by the supply of filtered L-DOPA and the Metabolism of dopamine via catechol-O-methyldopamine. The importance of dopamine as a natriuretic hormone is reflected by its capacity to inhibit the majority of renal tubule Sodium transporters. Notably, the activity of Na+, K+ ATPase is inhibited in most tubule segments by dopamine. Recent studies have elucidated many of the signaling pathways for renal dopamine receptors. Novel principles for homologous and heterologous sensitization of dopamine receptors have been detected that may explain some of the interaction between dopamine and other first messengers that modulate renal tubule Sodium transport. A broad understanding of the renal dopamine system has become increasingly important, since there is now strong evidence from both clinical and experimental studies that dysregulation of the renal dopamine system plays a role in many forms of multigenetic hypertension.
-
Activation/deactivation of renal Na+,K(+)-ATPase: a final common pathway for regulation of natriuresis.
FASEB journal : official publication of the Federation of American Societies for Experimental Biology, 1994Co-Authors: Anita Aperia, Ulla Holtbäck, Marie‐louise Syrén, Lill Britt Svensson, Jessica Fryckstedt, Paul GreengardAbstract:Renal Sodium Metabolism, a major determinant of blood pressure, is regulated with great precision by a variety of endocrine, autocrine, and neuronal factors. Although these factors are known to regulate Sodium Metabolism by affecting the rate of tubular Sodium reabsorption, the molecular mechanisms by which they act are poorly understood. Na+,K(+)-ATPase plays a pivotal role for Sodium reabsorption in all tubular segments. The activity of this enzyme can be dynamically regulated by phosphorylation and dephosphorylation. Here we summarize both old and new evidence that several major substances believed to be involved in the regulation of Sodium Metabolism and blood pressure, i.e., the antidiuretic agents angiotensin II and norepinephrine, and the diuretic agents dopamine and atrial natriuretic peptide (ANP), may achieve their effects through a common pathway that involves reversible activation/deactivation of renal tubular Na+,K(+)-ATPase. Regulation of Na+,K(+)-ATPase activity was studied using a preparat...
Chris N. Glover - One of the best experts on this subject based on the ideXlab platform.
-
The impacts of stress on Sodium Metabolism and copper accumulation in a freshwater fish.
Aquatic toxicology (Amsterdam Netherlands), 2013Co-Authors: Rachel A. Harley, Chris N. GloverAbstract:In freshwater fish, stress can often result in significant modifications to Na(+) Metabolism and may be an important aspect to consider in conservation efforts; as maintaining ion balance is critical to survival and ion transport is also a key determinant of metal toxicity. In order to better quantify the response of stress, Na(+) influx, Na(+) efflux, and copper accumulation were measured as a result of handling stress in inanga (Galaxias maculatus). This species is a culturally and economically important fish in New Zealand as one of the major species in the local 'whitebait' fishery. Na(+) influx rates in inanga were found to be 2-3 times greater after handling than in 'recovered' fish, and Na(+) efflux rates increased in the range of 5-6 times. Both influx and efflux rates quickly returned to resting levels within 24h. Increases in Na(+) efflux were strongly correlated with opercular beat frequency. This suggests an increas in ventilation, and subsequent enhanced diffusive loss of Na(+), as the mechanism of increased Na(+) efflux. Total body copper levels were also measured under similar treatments. Fish had significantly higher levels of copper directly after handling than following a 24h recovery; likely due to a shared Na(+)/copper uptake pathway. As accumulation is linked to toxicity, fish exposed to elevated copper levels in stressful environments will consequently be more at risk to metal toxicity. In a natural environment, stress can come from many different sources; among which, anthropogenic disturbances can often be a cause. Given that inanga must migrate through metal-contaminated coastal regions to reach breeding habitats, they will be exposed to toxicants under conditions where perfusion and ventilation of the gill is increased. As such, ion loss would be exacerbated, leading to an enhanced compensatory ion uptake and an increase in accumulation of ion-mimicking toxicants such as copper, exacerbating toxicity. This is a concern as conservation efforts in more disruptive environments may not be adequately protected.
-
Is the habitation of acidic-water sanctuaries by galaxiid fish facilitated by natural organic matter modification of Sodium Metabolism?
Physiological and biochemical zoology : PBZ, 2012Co-Authors: Chris N. Glover, Katherine A. Donovan, Jonathan V. HillAbstract:AbstractAcidic waters of New Zealand’s West Coast are hypothesized to be a refuge for native galaxiid fish, allowing them to escape predation from acid-sensitive invasive salmonid species. To determine the mechanisms by which galaxiids tolerate low pH, we investigated Sodium Metabolism in inanga Galaxias maculatus in response to water pH, short-term acclimation to acidic waters, the presence and source of natural organic matter (NOM), and fish life history. Contrary to expectation, inanga were physiologically sensitive to acid exposure, displaying inhibited Sodium influx and exacerbated Sodium efflux. Short-term (144 h) acclimation to acid did not modify this effect, and NOM did not exert a protective effect on Sodium Metabolism at low pH. Inanga sourced from naturally acidic West Coast waters did, however, display a Sodium influx capacity (Jmax) that was significantly elevated when compared with that of fish collected from neutral waters. All inanga, independent of source, exhibited exceptionally high so...
-
The disruption of Daphnia magna Sodium Metabolism by humic substances: mechanism of action and effect of humic substance source.
Physiological and biochemical zoology : PBZ, 2005Co-Authors: Chris N. Glover, Chris M. WoodAbstract:Abstract Humic substances have important functions in aquatic systems. While these roles are primarily indirect, influencing the physicochemical environment, recent evidence suggests these materials may also have direct biological actions. This study investigated the mechanism by which humic substances perturb Sodium Metabolism in a freshwater invertebrate, the water flea Daphnia magna. Aldrich humic acid (AHA) stimulated the maximal rate of whole‐body Sodium influx (Jmax) when experimental pH was 6 and water calcium content was 0.5 mM. This effect persisted at pH 8 and 1 mM calcium but not at pH 8 in the absence of calcium. An indirect action of AHA on apical transporter activity was proposed to explain this effect. At pH 4 AHA promoted a linear Sodium uptake kinetic relationship, attributed to altered membrane permeability due to enhanced membrane binding of humic substances at low pH. In contrast, a real‐world natural organic matter sample had no consistent action on Sodium influx, suggesting that impa...
-
Humic Substances Influence Sodium Metabolism in the Freshwater Crustacean Daphnia magna
Physiological and biochemical zoology : PBZ, 2005Co-Authors: Chris N. Glover, Eric F. Pane, Chris M. WoodAbstract:Abstract Humic substances are ubiquitous components of natural waters with important roles in alleviating metal toxicity to aquatic organisms. Recent literature reports suggest that humic substances may also exert direct influences on biota. This study investigated the influence of two commercially available humic substances on Sodium Metabolism in Daphnia magna, a hyperregulating freshwater crustacean. Environmentally realistic levels of Suwannee River natural organic matter (SRN) and Aldrich humic acid (AHA) significantly enhanced Sodium transport. This effect was described as an uncompetitive stimulation of Sodium influx, as characterised by an increased maximal Sodium transport rate (Jmax), accompanied by a decreased uptake affinity (increased Km). SRN exposure also significantly promoted the unidirectional loss of Sodium from the daphnids to the water, an effect not observed in the presence of AHA. A 24‐h preexposure to AHA before influx measurement had no effect on AHA‐induced stimulation of Sodium ...
V G Fagundes - One of the best experts on this subject based on the ideXlab platform.
-
Effects of long-term administration of isradipine on renal hemodynamics and Sodium Metabolism.
Journal of cardiovascular pharmacology, 1992Co-Authors: E A Francischetti, I Barroso, A Da Silva, V G FagundesAbstract:The objective of this double-blind, placebo-controlled study was to evaluate the effects of isradipine on renal hemodynamics and function. Ten patients with mild-to-moderate hypertension were given isradipine at 2.5 mg twice daily for 3 months after 4 weeks of placebo washout. Renal studies were performed 2 h after the morning administration of treatment. The results of these evaluations indicate that isradipine as monotherapy significantly reduced the mean arterial pressure, while the effective renal plasma flow was increased (+16%) and glomerular filtration rate remained virtually unchanged (-8.7 ml/min). The filtration fraction and renal vascular resistance decreased significantly. There was a significant decrease in the absolute rate of proximal Sodium reabsorption, and a significant increase in the distal reabsorption. Clearance of Sodium remained unchanged. In conclusion, monotherapy with low-dose isradipine was not only effective in controlling blood pressure, but also decreased the renal vascular resistance while avoiding glomerular hyperfiltration, and exerted a protective effect on renal hemodynamics. Natriuresis also remained stable despite the blood pressure reduction.
Da Silva A - One of the best experts on this subject based on the ideXlab platform.
-
Effects of long-term administration of isradipine on renal hemodynamics and Sodium Metabolism
Journal of Cardiovascular Pharmacology, 1992Co-Authors: E A Francischetti, Barroso I, Da Silva AAbstract:The objective of this double-blind, placebo-controlled study was to evaluate the effects of isradipine on renal hemodynamics and function. Ten patients with mild-to-moderate hypertension were given isradipine at 2.5 mg twice daily for 3 months after 4 weeks of placebo washout. Renal studies were performed 2 h after the morning administration treatment. The results of these evaluations indicate that isradipine as monotherapy significantly reduced the mean arterial pressure, while the effective renal plasma flow was increased (+16%) and glomerular filtration rate remained virtually unchanged (−8.7 ml/min)