Proximal convoluted tubule

SGLT2 is a low-affinity, high capacity sodium-glucose cotransporter located in the early proximal convoluted tubule SI segment. SGLT2 comprises 13... 

Renal 1.9 3.9 (yellow protein in tubule lumen eosinophilic droplets in cells of proximal convoluted tubules increased kidney weights) 23.4 M (proteinuria) ... 

H)2-D3 is a weak agonist and must be modified by hydroxylation at position Cj for full biologic activity. This is accomplished in mitochondria of the renal proximal convoluted tubule by a three-component monooxygenase reaction that requires NADPFl, Mg, molecular oxygen, and at least three enzymes (1) a flavoprotein, renal ferredoxin reductase (2) an iron sulfur protein, renal ferredoxin and (3) cytochrome P450. This system produces l,25(OH)2-D3, which is the most potent namrally occurring metabolite of vitamin D. 

RJ Alpern. (1985). Mechanism of basolateralmembrane II -OH /IICOL transport in the rat proximal convoluted tubule. A sodium-coupled electrogenic process. J Gen Physiol 86 613-636. 

Dietary route, 11 species, diagnosed as lead poisoned All had inclusions in proximal convoluted tubules of kidney liver lead residues ranged from 3.1 to 15 mg/kg fresh weight 12... 

Some deaths. Intranuclear inclusion bodies in cells of kidney proximal convoluted tubules... 

Except for its lower protein concentration, glomerular filtrate at the top of the nephron is chemically identical to the plasma. The chemical composition of the urine is however quantitatively very different to that of plasma, the difference is due to the actions of the tubules. Cells of the proximal convoluted tubule (PCT) are responsible for bulk transfer and reclamation of most of the filtered water, sodium, amino acids and glucose (for example) whereas the distal convoluted tubule (DCT) and the collecting duct are concerned more with fine tuning the composition to suit the needs of the body. 

R. Krapf, C. A. Berry, and A. S. Verkman, Estimation of intracellular chloride activity in isolated perfused rabbit proximal convoluted tubules using a fluorescent indicator, Biophys. J. 53, 955-962 (1988). 

PCT is proximal convoluted tubule, DL is descending limb of the loop of Henle, Thin AL is thin ascending limb of the loop of Henle, Thick AL is thick ascending limb of the loop of Henle, DCT is distal convoluted tubule and CD is collecting duct. (This figure is reproduced with permission from Fundamental Principles and Practice of Anaesthesia, P. Hutton, G. Cooper, F. James and J. Butterworth. Martin-Dunitz 2002 pp. 487, illustration no. 25.16.)... 

M (nephropathy enlarged nuclei of the epithelial cells of the proximal convoluted tubules mineralization in the cortex)... 

Additional studies of decalin exposure in rats have characterized the specific sequence of renal alterations first the variable occurrence of light-microscopically evident proximal convoluted tubule epithelial cell necrosis, presumably a reflection of cellular injury associated with excessive protein accumulation (hyaline droplets) then the occurrence of granular casts at the junction of the inner and outer bands of the outer zone of the medulla and finally, chronic nephrosis, occurring secondary to tubular obstruction by granular casts. It is not... 

A nephron, showing the major sites and percentage (in braces) of sodium absorption along with other features of solute transport. The filtered load = GFR (180 L/day) Xplasma Na+ (140 mEq/L) or 25,200 mEq/day. About 1% of this amount is excreted in voided urine. Sites where tubular fluid is isosmotic, hypertonic, or hypotonic relative to plasma are shown. POT, proximal convoluted tubule LH, loop of Henle DOT, distal convoluted tubule CCD, cortical collecting duct TAL, thick ascending loop. 

Carbonic anhydrase-medlated Na+/H+ exchange In proximal convoluted tubule. Na+/H+exchange across apical cell membranes Is shown by the open circle. Carbonic anhydrase (CA) is present in a membrane-bound form in the apical membrane and a soluble form within the cytoplasm. The Na+/K+-ATPase is shown by the filled circle at the basolateral membrane. 

An important functional characteristic of the proximal tubule is that fluid reabsorption is isosmotic that is, proximal reabsorbed tubular fluid has the same osmotic concentration as plasma. Solute and water are transported in the same proportions as in the plasma because of the high water permeability of the proximal tubule. Thus, the total solute concentration of the fluid in the proximal convoluted tubule does not change as the fluid moves toward the descending loop of Henle. The corollary of this high water permeability is that unabsorbable or poorly permeable solutes in the luminal fluid retard fluid absorption by proximal tubules. This is an important consideration for understanding the actions of osmotic diuretics. 

Suramin is not absorbed from the intestinal tract and is administered intravenously. Although the initial high plasma levels drop rapidly, suramin binds tightly to and is slowly released from plasma proteins, and so it persists in the host for up to 3 months. Suramin neither penetrates red blood cells nor enters the CNS. It is taken up by the reticuloendothelial cells and accumulates in the Kupffer cells of the liver and in the epithelial cells of the proximal convoluted tubules of the kidney. It is excreted by glomerular filtration, largely as the intact molecule. 

Mechanism of Action An antigout agent that competitively inhibits reabsorption of uric acid at the proximal convoluted tubule. Also, inhibits renal tubular secretion of weak organic acids, such as penicillins. Therapeutic Effect Promotes uric acid excretion, reduces serum uric acid level, and increases plasma levels of penicillins and cephalosporins. 

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