Richards and his group showed, about 40 yr ago, that the blood is filtered in the glomerulus. The largest portion of the water and solutes of the filtered fluid is absorbed across the proximal tubular wall, toward the peritubular blood capillaries (see 17). Thus, proximal tubular absorption is a process of paramount importance in the maintenance of homeostasis (1, 16). I shall review here studi...

Angiotensin-converting enzyme 2 (ACE2) is highly expressed in the kidney proximal tubule, where it cleaves angiotensin (Ang) II to Ang-(1-7). Urinary ACE2 levels increase in diabetes, suggesting that ACE2 may be shed from tubular cells. The aim of this study was to determine if ACE2 is shed from proximal tubular cells, to characterize ACE2 fragments, and to study pathways for shedding. Studies ...

The role of calcium-activated chloride channels for renal function is unknown. By immunohistochemistry we demonstrate dominant expression of the recently identified calcium-activated chloride channels, Anoctamin 1 (Ano1, TMEM16A) in human and mouse proximal tubular epithelial (PTE) cells, with some expression in podocytes and other tubular segments. Ano1-null mice had proteinuria and numerous l...

We report a case of congenital renal proximal tubular dysfunction (CRPTD) accompanied by IgA nephropathy. The mesangial matrix was slightly increased with depositions of IgA and C3. Podocytes contained many clear vacuoles. Cuboidal cells, as well as squamous cells, lined the parietal epithelium of Bowman's capsule, although the functional or pathological significance of the cuboidal cells is un...

Most chronic kidney disease in infants and children results from congenital anomalies of the kidneys and urinary tract, including obstructive nephropathy. Although less common, inherited disorders such as polycystic kidney disease (PKD) and cystinosis also lead to progressive tubular injury and nephron loss. At the present time, therapies to slow progression of kidney disease are mainly directe...

BACKGROUND Adenosine A(1) receptor blockade has been suggested as a treatment in conditions with sodium and fluid retention because it increases urinary Na(+) excretion and increases proximal tubular fluid output. In the present study, we examine the time course for the renal responses to adenosine A(1) receptor blockade in order to investigate whether the effects may be prolonged and not just ...

The effects of hyperglycemia and hyperinsulinemia on renal handling of sodium, calcium, and phosphate were studied in dogs employing the recollection micropuncture technique. Subthreshold sustained hyperglycemia resulted in an isonatric inhibition of proximal tubular sodium, fluid, calcium, and phosphate reabsorption by 8-14%. Fractional excretion of sodium and phosphate, however, fell (P is le...

BACKGROUND The anticancer drug cisplatin is know to have toxic side-effects on different segments of the nephron. The flavonoid silibinin has previously been shown to be protective in models of hepatotoxicity. The aim of the present study was to evaluate, whether silibinin can also ameliorate alterations in renal glomerular and tubular function and tubular morphology induced by cisplatin. MET...

To determine the sites of tubular phosphate reabsorption in the nephron, microinjection studies were undertaken, utilizing isotonic electrolyte solutions, containing either 1.4 or 8.0 mM phosphate and radioactive PO(4)-(33)P and inulin-(3)H, in rats made mildly diuretic by infusion of mannitol. The injected sites were localized by the technique of latex dissection. The relation between proximal...

The "extracellular cAMP-adenosine pathway" refers to the conversion of cAMP to AMP by ecto-phosphodiesterase, followed by metabolism of AMP to adenosine by ecto-5'-nucleotidase, with all the steps occurring in the extracellular compartment. This study investigated whether the extracellular cAMP-adenosine pathway exists in proximal tubules. Freshly isolated proximal tubules rapidly converted bas...