Seminars in nephrology
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During the past century, investigators have increased our understanding of renal potassium excretion significantly using many techniques. Notable among these were renal clearance experiments, renal micropuncture, isolated tubule microperfusion, and electrophysiological and patch clamp analysis. These experiments have been made possible by technical advances that have allowed the measurement of potassium in progressively smaller quantities. ⋯ Additional micropuncture and microperfusion studies showed that a component of potassium secreted by the distal cortical nephron and cortical collecting duct is reabsorbed in the medullary collecting duct, which results in renal medullary potassium recycling. Studies have defined the cellular and molecular mechanisms responsible for potassium secretion and potassium reabsorption in the collecting duct. Further understanding of renal potassium handling will require integrated investigation of the renal and extrarenal signaling systems that control these transport mechanisms.
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It has been known for decades that urinary potassium excretion varies with a circadian pattern. In this review, we consider the historical evidence for this phenomenon and present an overview of recent developments in the field. ⋯ We propose the circadian clock mechanism as a key regulator of renal potassium transporters, and consequently renal potassium excretion. Further investigation into the regulation mechanism of renal potassium transport by the circadian clock is warranted to increase our understanding of the clinical relevance of circadian rhythms to potassium homeostasis.
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Seminars in nephrology · Nov 2012
ReviewHigh-output heart failure: how to define it, when to treat it, and how to treat it.
Although hemodialysis patients who initiate and maintain a permanent form of dialysis vascular access have improved all-cause and cardiovascular survival compared with those who use catheters, the presence of an arteriovenous fistula has been shown to have a short-term, adverse effect on cardiac function. Through its effect as a left-to-right extracardiac shunt, the arteriovenous fistula can increase cardiac workload substantially, and, in certain patients, result in a high-output state and resultant heart failure over time. Here we review the mechanisms by which dialysis arteriovenous access may promote the development of high-output cardiac failure in end-stage renal disease patients, describe risk factors for and the diagnosis of high-output heart failure, and suggest management strategies for patients who develop high-output heart failure.
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Seminars in nephrology · Jan 2012
ReviewRole of biomarkers in the diagnosis and management of cardio-renal syndromes.
The complex interaction between heart and kidney disease has been increasingly recognized over the recent years. Pathologies within these two organs frequently coexist and, due to organ cross-talk, dysfunction in one often leads to problems in the other. ⋯ To aid in the diagnosis, management and prognosis of these conditions, many novel cardiac and renal biomarkers have emerged to supplement traditional markers which have limited specificity and sensitivity. In this review we will summarize the literature on novel renal behind these and other biomarkers and discuss their potential relevance to the clinical scenarios of cardio-renal syndrome.
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Seminars in nephrology · Jan 2012
ReviewCardio-renal syndrome type 3: epidemiology, pathophysiology, and treatment.
A complex pathophysiology, cardio-renal syndrome (CRS), has been redefined in recent years. One subtype is acute renocardiac CRS, or CRS type 3. This syndrome is intended to comprise situations in which acute kidney injury (AKI) results in acute cardiac injury or dysfunction. ⋯ Results obtained from studies using a standard definition of AKI can lead us to the next step of early recognition, prevention, therapeutic intervention, and improved quality of care. Novel biomarkers and therapeutic interventions for primary and secondary disorders are being developed and tested. The hope is that improved outcomes will follow.