Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P41181 (collecting duct)
 5,183 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Thirty minutes after indomethacin (10 mg/kg, iv), a prostaglandin synthesis inhibitor, had been given to 10 rats, the Na concentration in renal papilla averaged 349 mEq/kg H2O, whereas it averaged only 181 in 14 "non-indomethacin" control rats (P less than 0.0001). Papillary plasma flow was closely similar in both groups. In a subsequent study, eight "indomethacin" rats had the same papillary flow as seven non-indomethacin rats but had a papillary Na concentration of 358 vs. 185 in the non-indomethacin controls (P less than 0.0001). In nine more rats, indomethacin increased Cl concentration in papillas by 66% (P less than 0.0001), while Na concentration increased 60% (P less than 0.0001). In eight other rats, micropuncture indicated that indomethacin does not greatly alter delivery of fluid out of late proximal tubule. Meclofenamate, another inhibitor, increased papillary Na just as much as indomethacin. Papillary urea is not changed with indomethacin. Thus, papillary Na concentration was almost twice as high in indomethacin rats, despite similar papillary plasma flow and late proximal flow. Apparently, inhibiting prostaglandin synthesis is associated with either a great increase in Na or Cl "pumping" or a great decrease in Na or Cl "leak" in either collecting duct or ascending limb, or in both. The collecting duct and papillary interstitial cells both synthesize prostaglandins, which seem to have a profound effect on medullary net Na transport.
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PMID:Evidence that prostaglandin synthesis inhibitors increase the concentration of sodium and chloride in rat renal medulla. 87 Feb 22

The effects of acute hypercalcemia on hemodynamics and on water and sodium excretion were studied on the blood-perfused isolated dog kidney. This model advantageously eliminates various factors which modify medullary osmolality and intrarenal hemodynamics, as well as collecting duct permeability. Calcium ion directly inhibits sodium reabsorption in the proximal tubule and in the ascending limb of Henle's loop, leading to increased sodium excretion rate and to decreased free water generation. The vasoconstrictive action of calcium, leading to decreased glomerular filtration rate, may mitigate the strong natriuretic effect of this ion.
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PMID:Effects of hypercalcemia on water and sodium excretion by the isolated dog kidney. 94 13

The administration of diphenylamine to rats induces an acquired form of cystic disease. In order to examine the early changes in this model of experimental cystic disease prior to the development of the more severe structural alterations, clearance, micropuncture, and morphologic studies were performed in rats fed DPA for 3 to 6 weeks. A significant defect in maximal urine concentrating ability (Umax) was manifest by the second week and averaged 50% of control values. Further studies were undertaken to examine the cause of the defect in Umax. Whole-kidney glomerular filtration rate (GFR), single-nephron GFR, end-proximal TF/Pinulin, glucose and bicarbonate reabsorption were all normal, indicating normal function of the proximal tubule. Free water clearance and free water reabsorption were not significantly different in DPA-treated rats as compared to controls, suggesting normal function of the ascending limb of the loop of Henle and collecting duct. Morphologic examination revealed gross cysts in less than 10% of the kidneys but structural changes were consistently demonstrated in the collecting ducts of DPA-treated rats. These studies indicate that the decrease in Umax in DPA-treated animals is the result of a defect located at the terminal portion of the collecting duct.
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PMID:Renal function in experimental cystic disease of the rat. 95 92

The anatomy and ultrastructure of the lizard kidney (Sceloporus cyanogenys) have been studied by light and electron microscopy. The number of glomeruli was counted in serial sections and estimated to be 2,000 (in the two kidneys). Beginning with the glomerulus and Bowman's capsule the nephron segments are sequentially: (a) proximal tubule; (b) intermediate ciliated segment consisting of a proximal and distal part; (c) distal tubule, which can be divided into two segments, followed by (d) connecting tubule and (e) initial collecting duct. The initial collecting ducts from several nephrons open into the collecting duct. Tubular epithelium in this lizard has similarities to that of other reptiles. The lateral borders do not overlap like in mammals, but interdigitate by fingerlike projections. The length of the nephron segments was measured in disected tubules and the diameter was measured on light and electron micrographs. From these measurements estimates of inner tubular surface area were made. Together with data from physiological studies (Stolte et al., '76; Schmidt-Nielsen, '76) the estimated surface area was used to calculate transport rates per unit area across the epithelium. Comparisons of structure and transport rates per unit area across the epithelium. Comparisons of structure and transport rates were made between S. cyanogenys and other reptiles and mammals.
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PMID:Anatomy and ultrastructure of the excretory system of the lizard, Sceloporus cyanogenys. 95 43

Studies were carried out, using transmission electron microscopy, of the cilia of the nephrons of rat and human kidneys. Cilia were observed in the parietal layer of Bowman's capsule, in the proximal tubule, the distal tubule, including the macula densa, and the collecting duct. They had a number of characteristic features, including the presence of a centriole adjacent to the basal body, long, slender cross-striated rootlets, and a typically organized basal body. The shaft of the cilia differed from the typical 9 + 2 pattern of organization. Near the base of the cilia the pattern was 9 + 0. In the middle portion, one or more of the peripheral doublets had been displaced centrally to give an 8 + 1 or a 7 + 2 pattern, while towards the tip the pattern became more irregular and the doublets were reduced to single microtubules. We have hypothesized that these cilia may be vestigial. They may, if motile, have some minor stirring function, or they may play a sensory role, as has been postulated for similarly structured cilia in other sites.
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PMID:Fine structure of mammalian renal cilia. 115 3

The concentration of nine endogenous free L-alpha-amino acids (ALA, LEU, ILE, PHE, TYR, LYS, GLU, PRO, GLY) and of taurine were determined simultaneously along the nephron of the rat kidney using free-flow micropuncture techniques without altering plasma amino acid concentration or kidney function. The amount of each amino acid was determined after dansylation (14C-labelled dansyl-chloride) in the micropuncture sample followed by thinlayer chromatography. The main site of reabsorption is the proximal tubule. After 15-20% of the proximal tubule length the bulk of reabsorption has taken place (18.9 plus or minus 3.4% S.E. of the filtered load remaining). Net reabsorption continues to a small but significant extent along the distal nephron (disal tubule and collecting duct). Reabsorption of taurine is less rapid (% remaining of filtered load at the early proximal tubule 37.0 plus or minus 4.6%). The transtubular concentration ratio of all amino acids except taurine follows a homogeneous course. Under the experimental conditions of this study no distction with respect to different systems of reabsorption "neutral", "basic", "acidic", "imino-glycine") could be made.
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PMID:Amino acid reabsorption in the rat nephron. Free flow micropuncture study. 117 57

Firstly details are collected concerning the required parameters of a simple linear regression in order to evaluate statistically results of measurements, which can also be present in the form (chii, yi +/- SDi). In this way lines of regression are determined for connections between the kidney weight and the body weight, between the lengths of the proximal tubules (and the proximal convolution) of the three various types of nephron and the kidney weight, between the length of the distal convoluted tubule, likewise the number of glomerula, and the kidney weight and finally between the single nephron filtration rate and the length of the proximal tubule. Starting from a model body weight for the rat of 200 g and considering the percentage of thin segments in the tissue of the renal pyramid, a loop of Henle with a length of 8.1 mm for the thin part and a length of 2.4 mm for the ascending thick limb was calculated for the model nephron from the lengths of the loops of the three types of nephrons. In contrast to former model formulations concerning the collecting duct system, the tree-like branched structure was considered for the first time and a linear approximation to the relation between both the circumference line and the cross section area and the lenggh of the collecting ducts was determined. The geometric model relates only to the tubular system and takes no notice of the blood vessels.
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PMID:A geometric model of the rat kidney. 120 Mar 99

These results are consistent with a model for renal tubular transport of urate in which there is reabsorption of both filtered and secreted urate. Urate secretion greatly exceeds total urate excretion, and most secreted urate is reabsorbed. At least a portion of urate reabsorption occurs at a site distal to or coextensive with the urate secretory site. There appear to be at least two distinct reabsorptive mechanisms for urate. The results of the flow rate and vasopressin studies are consistent with the hypothesis that urate reabsorption occurs in both the distal and the proximal tubule in man. The distal reabsorptive site appears to be quite small. It may be passive since it does not appear to be inhibited by uricosuric drugs. This reabsorptive site may account for less than 15% of total urate reabsorption. Both volume expansion and probenecid may inhibit urate absorption only in the proximal tubule. Thus reabsorption in the proximal tubule coud account for more than 90% of total urate reabsorption. Reabsorption at the postulated collecting duct reabsorptive site appears to be too small in magnitude to account for all reabsorptions of secreted urate. This could be explained if the reabsorptive site in the proximal tubule is coextensive with or distal to the secretory site. Alternatively, there might be two reabsorptive sites in the proximal tubule: a presecretory site accounting for the reabsorption of most filtered urate, and a site either coextensive or distal to the secretory site accounting for a major component of reabsorption of secreted urate. Finally urate reabsorption would also take place in the collecting duct, perhaps at a passive, flow-dependent site.
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PMID:Postsecretory reabsorption of urate in man. 120 Nov 24

In a recent micropuncture study electrodes with relatively large tips (3 to 5 mu O.D.) and, hence, low tip resistances were used to measure the transepithelial potential difference (PD) across the proximal tubule of the rat kidney. The present study reexamines the PD of the distal tubule of the rat kidney using such electrodes. In contrast to previous studies where a negative PD has been uniformly found in the distal tubule, the transtubular PD was found to be positively oriented (+3.7 mv) when particular efforts were made to puncture the earliest accessible segments. In accord with previous observations, the PD of the late segment was consistently negative (mean, -19.6 mv). Morphologic examination of the epithelium at the site of puncture suggests that in the very early distal tubule where positive potentials are recorded, the epithelium is characteristic of the distal convoluted tubule. By contrast, in the latter part of the distal tubule, where negative potentials are recorded, the epithelium displays the morphologic characteristics of the cortical collecting duct. The results of these studies suggest that the net transport properties of the distal tubule, that is the region of the nephron beginning just beyond the macula densa and extending to the first junction with another renal tubule, are a composite of activities of at least two types of epithelium.
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PMID:Transepithelial potential difference profile of the distal tubule of the rat kidney. 120 53

1; The tubule of kidney of Gasterosteus aculeatus L. consists of four histologically different regions: Proximal tubule I and III, connection segment and collecting tubule. 2. All of tubule segments inclusively the urinary duct out of the proximal tubule I are showing synthesis of secretion. 3. There are producing two various secretion in two distinct species of cells. From the cells of proximal tubule II are secreted and extruded a granular secretion and from the cells of abducted urinary ducts (connection segment, collecting duct and urinary duct) a hyalo-mucous secretion. 4. During the breeding season the morphological variationes were divided into three stadiums, the stadium of differentiation, of producing of secretion and of reproduction. In second stadium were differenced three phases, in particular characterizing by rhythmical variationes of nucleus structure and synthesis of secretion as extrustion. 5. There are discussing the parallels to synthesis of secretion in glandular cells.
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PMID:[Histological and histochemical studies of the kidney of stickleback Gasterosteus aculeatus L. I. Morphological changes of the kidney epithelial cells during the spawning period]. 122 69


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