Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0403608 (ureter)
 9,655 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Changes in the excretion of water and electrolyte in one kidney after exclusion of its partner have been studied in anesthetized dogs and rabbits. Complete clamping of the contralateral kidney pedicle or ureter results in a rapid increase in the excretion of water, sodium, potassium, chloride, calcium, phosphate and bicarbonate. This response is also observed in denervated kidneys. Pretreatment with the loop inhibitor, furosemide, does not preclude adaptation which, however, is blunted by acetazolamide, an inhibitor of proximal sodium and bicarbonate reabsorption. Free-water reabsorption during hypertonic saline diuresis is normal in the remaining kidney. Compensatory adaptation, thus, appears to be located in the proximal tubule. The regulatory response to contralateral kidney exclusion is already fully developed in one-month-old rabbits. Compensatory adaptation of electrolyte excretion is not accounted for by changes in extracellular fluid volume, plasma composition, glomerular filtration rate, effective renal plasma flow, aldosterone or vasopressin.
 ...
PMID:Studies on compensatory adaptation of renal functions. 73 47

The renal and proximal tubule response to contralateral kidney exclusion was studied in a variety of circumstances. Recollection micropuncture studies were performed to assess the response to contralateral kidney clamping in the normal or a remnant kidney of the dog. Acute clamping of the contralateral kidney for a normal and unilateral remnant kidney resulted in marked reduction in proximal TF/P inulin ratios in the experimental kidney reflecting a 15 percent reduction in fluid reabsorption. Mean fractional excretion of sodium, potassium and water increased significantly in remnant kidney dogs but no significant change was observed in normal dogs except for potassium excretion. The marked reduction in proximal reabsorption occurred as soon as 5-15 minutes after contralateral kidney clamping and was compensated by distal reabsorption. Acute obstruction of the contralateral ureter results in a similar markedly reduced proximal tubular reabsorption. The reduction in proximal reabsorption induced by contralateral clamping occurred in the presence of reduced perfusion pressure and volume expansion and to some extent with renal denervation. When prostaglandin E(2) or acetycholine were infused prior to contralateral kidney clamping, proximal reabsorption remained at control levels and the contralateral clamping response was blocked. Similar blockade occurred after treatment with indomethacin. Acute reduction in nephron mass causes a marked depression of proximal tubular sodium and fluid absorption not obviously accounted for by hemodynamicphysical factors and humoral factors may be involved. The level of distal reabsorption to increased proximal delivery following contralateral clamping, determines the net urinary excretion.
 ...
PMID:Acute functional adaptation to nephron loss: micropuncture studies. 73 48

This study explores the role of brush border (luminal) membranes in p-aminohippurate (PAH) transport by the rabbit kidney. Under control conditions PAH appears in urine at the same rate as simultaneously injected inulin; no evidence for a secretory delay was found. After suppression of secretion by limiting concentrations of Benemid (probenecid), urinary PAH is largely derived from glomerular filtrate: its tubular transit time exceeds that of inulin. Excess Benemid abolishes this delay. Filtered PAH on its way to excretion appears to be permitted by a mechanism sensitive to high concentrations of Benemid to pass through an extraluminal volume equivalent to that of the proximal tubule cells. These results strengthen the previously suggested model for tubular PAH transport, and provide justification for use of glomerulus-to-ureter transit times in localizing tubular transport mechanisms.
 ...
PMID:Movement of p-aminohippurate between lumen and cells of renal tubule. 87 Nov 64

We evaluated urinary excretion and tubular transport of 3H-digoxin by three different methods in anesthetized rats made diuretic by infusion of 2.5% saline. In one group small volumes of 3H-digoxin and 14C-inulin were injected simultaneously into surface proximal convolutions, and urine was collected serially from both ureters. Digoxin recovery was lower after early (62.1 +/- 5.3%) than after late (86.9 +/- 7.7%) proximal administration but inulin recovery was complete (99.6 +/- 2.7%) after all injections. Most of the digoxin was excreted simultaneously with inulin. Delayed recovery was low. In another group of rats digoxin and inulin were applied directly to the capsule of the left kidney. Two-thirds of the recovered digoxin appeared from the left ureter and one-third from the right. The difference (41.9 +/- 7.4%) is an estimate of transtubular digoxin influx. Digoxin excretion preceded inulin only on the left. Digoxin to inulin concentration ratios were 6 times higher from the left than the right, whereas inulin recoveries from the two sides were similar. In a third group of rats tubular fluid was collected from surface convolutions of proximal and distal tubule. In the accessible segment of the proximal tubule 35.9% of the filtered digoxin was reabsorbed. In the more distal nephron, drug was added into the lumen; this resulted in a net urinary excretion of 80.2 +/- 18.2%. These findings are compatible with free filtration of digoxin at the glomerulus followed by passive proximal tubular reabsorption and an influx against a concentration gradient in the distal nephron.
 ...
PMID:Renal tubular transport of 3H-digoxin in saline diuresis in rats. 124 66

Enzyme histochemistry was assessed in semi-thin glycolmethacrylate sections after 100 mg/kg 2-bromoethanamine (BEA) hydrobromide had been given ip to male Wistar rats to induce renal papillary necrosis. Changes in the proximal tubular marker enzymes alkaline phosphatase (Alk Phos), gamma-glutamytranspeptidase (GGT) and adenosine triphosphatase (ATPase) were not apparent before 8 hr, but there was a progressive loss up to 144 hr. The proteinaceous PAS-positive casts in the loops of Henle and the collecting ducts stained for Alk Phos and GGT (from 12 hr) and for ATPase (from 18 hr). Acid phosphatase (Acid Phos) staining was increased in the proximal tubule lysosomes from 18 hr. There was a marked increase in Alk Phos in all hyperplastic upper urothelial cells from 8 to 24 hr, and a mosaic of staining remained in the pelvis adjacent to the necrosed papilla at 144 hr. At 12 hr, there was an increase in the staining of the pelvic, ureter and bladder vascular endothelial ATPase, the intensity and area of which increased progressively from 18 hr and almost occluded the capillary lumens in the worst affected areas by 144 hr. These data show several distinct series of pathological changes after the administration of BEA. The subtle degenerative changes in the proximal tubule followed the papillary lesion, but exfoliated brush border and proximal tubular cells were important components of the protein casts in the distal nephron. Similarly, the intense Alk Phos staining in the hyperplastic regions of the upper urothelium and the increased pelvic, ureteric and bladder endothelial ATPase staining suggested they develop as a consequence of the papillary lesion.
 ...
PMID:Enzyme histochemical changes in an acutely induced renal papillary necrosis. 197

Urinary N-acetyl-beta-D-glucosaminidase (NAG), a lysosomal hydrolase located the proximal tubule of the kidney, has been used as a marker for subtle renal injury. In humans and other animals with diabetes mellitus, urinary NAG activity has been shown to increase within 12 hours of the onset of hyperglycemia and glycosuria. Whether the rise in urinary NAG activity is in response to the hyperglycemia or to the osmotic diuresis associated with glycosuria is not known, nor has the time course of the rise in enzyme activity been determined. A study was designed using four groups of dogs to examine these possibilities: group 1 (n = 5), control dogs; group 2 (n = 5), mannitol-infused dogs; group 3 (n = 5), low-glucose dogs; and group 4 (n = 5), high-glucose dogs. In groups 2 and 4, mannitol and glucose, respectively, were infused at a rate to double urine flow from the left ureter without altering the contralateral urine volume. In group 3, sufficient glucose was infused to elevate left renal vein glucose level without producing glycosuria. In the control dogs infused with normal saline solution at a constant rate throughout the control and study periods, no differences were found in urinary NAG excretion when data from individual clearance periods were compared for the right and left kidneys. In the low-glucose dogs, urinary NAG/creatinine ratios were significantly increased (P less than 0.01) when the left and right kidneys were compared for the duration of the infusion.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Differential response of urinary N-acetyl-beta-D-glucosaminidase to two osmotic diuretics in the dog. 392 47

The uptake and retention of a radiolabeled synthetic progestin, ORG 2058, was studied in the urinary tract of the female baboon. Four estrogen-primed baboons were injected intravenously with 2.5 micrograms./kg. body weight of 3H-ORG 2058. One animal, which served as a control, received an additional injection of 2.5 mg./kg. body weight of unlabeled progesterone. One hour after the injections, the animals were killed and the kidneys, ureters and urinary bladder were removed and processed for autoradiography. Localization of progestin was observed in the nuclei of the convoluted and straight segments of the distal tubule, the ascending thick limb of the loop of Henle and both cortical and medullary collecting tubules. Connective tissue cells were also labeled in the medulla and cortex of the kidney. An absence of silver grains was noted in the renal corpuscle, all segments of the proximal tubule and the thin loop of Henle. Concentration of the tritiated steroid was not observed in either the ureter or bladder or in any portions of the urinary tract of the control animal. This study suggests that progesterone has a direct effect via a progesterone specific receptor on the various target cells that sequestered the 3H-ORG 2058.
 ...
PMID:Progesterone--specific binding sites in the kidney of the female baboon. 620 45

The construction of renal lobules in Triturus (Cynops) pyrrhogaster was studied by reconstruction from serial semithin sections, and the structure of nephrons, collecting ducts and ureters was investigated by means of light and electron microscopy. In T. pyrrhogaster the kidney was mesonephros in construction; renal lobules were arranged segmentally and each of them sent one ureter. Male ureters ran caudally and met together before joining the Wolffian duct. In renal lobules, long collecting ducts ran medio-laterally in the dorsal aspect of the kidney and sent several branches ventrally. Each branch duct or short collecting duct received one nephron. Each nephron had five segments; 1) renal corpuscle, 2) ciliated neck segment with or without a naphrostome, 3) proximal tubule, 4) ciliated intermediate segment and 5) distal tubule. Proximal and distal tubules were segregated spacially in renal lobules and occupied the peripheral and central zone respectively. The filtration barrier of the glomerulus consisted of both the basal lamina of podocytes and the subendothelial connective tissue, and was much thicker than the mammalian filtration barrier. Proximal tubule cells had a brush border, apical specialization for reabsorption of organic materials and well-developed smooth endoplasmic reticulum, but few baso-lateral interdigitations. In distal tubule cells, baso-lateral interdigitations and infoldings were well-developed. Collecting duct cells had a sparse cytoplasm. Ureter cells in males contained many secretory granules. On the basis of structural organization of the newt kidney as well as physiological data in literature, we suggest that in land vertebrates proximal tubules were primarily adapted to reabsorption of organic materials and distal tubules to reabsorption of electrolytes and water.
 ...
PMID:The structure of the kidney of Japanese newts, Triturus (Cynops) pyrrhogaster. 683 32

In previous reports from this laboratory we have suggested that a reduction in medullary tonicity decreases the thin ascending loop of Henle sodium reabsorption and is in part responsible for the magnitude for the natriuresis accompanying 10% body weight Ringer loading. According to this postulate, one would expect that the medullary washout associated with water diuresis would also result in a natriuresis, but this does not occur. It is possible, however, that increased delivery from the proximal tubule is necessary to demonstrate an effect of medullary tonicity on urinary sodium excretion. Micropuncture studies were designed to test that possibility by increasing distal delivery by 2% Ringer loading in animals with and without reduced medullary tonicity. In an initial series of experiments the alpha-adrenergic agonist clonidine was used to induce a water diuresis. When given alone, this agent caused a marked decrease in urine osmolality and an increase in urine flow rate but had no effect on proximal reabsorption in either superficial or juxtamedullary nephrons, and did not alter urinary sodium excretion. Volume expansion with 2% body weight Ringer solution resulted in a significant fall in proximal reabsorption and a trivial increment in sodium excretion. When this same degree of volume expansion was conferred on animals undergoing a water diuresis, a marked increase in absolute and fractional sodium excretion occurred. In a second group of studies medullary tonicity was reduced in the left kidney only by removal of the left ureter 1 h before micropuncture. When these animals were infused with 2% body weight Ringer solution, proximal reabsorption was decreased in juxtamedullary nephrons, and a marked increase in sodium excretion was observed only from the left kidney. Finally, the effect of water diuresis on fractional sodium delivery to the early and late distal tubule of superficial nephrons during 2% Ringer loading was evaluated. Delivery to both of these sites was comparable after 2% Ringer loading alone and during 2% Ringer loading plus water diuresis. From these data, we conclude that medullary tonicity does influence renal sodium handling but that this effect is manifest in the final urine only under conditions in which proximal reabsorption is decreased. The data also suggest that this effect is limited to juxtamedullary nephrons and is probably localized to the thin ascending limb of the loop of Henle.
 ...
PMID:Effect of medullary tonicity on urinary sodium excretion in the rat. 707 54

Insulin-like growth factor-I (IGF-I) is a peptide growth factor whose activity is modulated by interaction with the family of six IGF binding proteins (IGFBPs). IGF-I is detected in rat kidney and has metabolic and growth effects. We have used in situ hybridization to localize mRNAs for the IGFBPs in rat kidney. Messenger RNAs for all six IGFBPs were detected, each with a distinctive distribution. IGFBP-1 mRNA was expressed in the distal nephron, from the thick ascending limb of the loop of Henle to the cortical collecting ducts. IGFBP-2 mRNA expression was confined to epithelial cells of the glomeruli and the thin limbs of the loop of Henle. IGFBP-3 mRNA was localized to the cortical interstitium while IGFBP-4 was the only IGFBP mRNA found in the proximal tubule. IGFBP-5 mRNA, the most abundant and widely distributed of the IGFBP mRNAs in the kidney, occurred in the glomerular mesangium and the medullary interstitium as well as in the epithelial cells of the distal nephron. IGFBP-6 mRNA, the least abundant, was expressed mainly in fibroblasts associated with renal blood vessels and the ureter. This heterogeneous distribution of the IGFBPs may enable IGF action to be regulated by multiple factors in a site-specific manner.
 ...
PMID:Localization of mRNAs for insulin-like growth factor binding proteins 1 to 6 in rat kidney. 756 7


1 2 Next >>