To produce a concentrated urine, the renal medulla needs hypertonicity for the reabsorption of free water from collecting duct. The single effect that increases interstitial tonicity in the outer medulla is the active NaCl reabsorption in the thick ascending limb, while the single effect in the inner medulla is the passive efflux of NaCl through the thin ascending limb. The passive mechanism in...

To explore the role of urea in the urinary concentrating mechanism, the contents of vasa recta, Henle's descending limbs and collecting ducts were sampled by micropuncture of the renal papilla before and after infusion of urea in 10 protein-depleted rats. Eight protein-depleted rats not given urea were similarly studied as a control group. After urea administration, osmolality and the concentra...

We reported that feeding rats 8% protein for 3 wk induces net urea transport and morphologic changes in initial inner medullary collecting ducts (IMCDs) which are not present in rats fed 18% protein. In this study, we measured net urea transport in microperfused initial IMCDs from rats fed 8% protein for > or = 3 wk and tested the effect of inhibiting Na+/K(+)-ATPase activity and found that add...

N,N?-linked oligoureas are a class of enantiopure, sequence-defined peptidomimetic oligomers without amino acids that form well-defined and predictable helical structures akin to the peptide ?-helix. Oligourea-based foldamers combine number features—such as synthetic accessibility, sequence modularity, folding fidelity—that bode well for their use in range applications from medicinal chemistry ...

background: hemodialysis is a process of removing waste and excess fluid from blood when kidneys cannot function efficiently. it often involves diverting blood to the filter of the dialysis machin to be cleared of toxic substances. fouling of pores in dialysis membrane caused by adhesion of plasma protein and other toxins will reduce the efficacy of the filtre. objective: in this study, the inf...