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

Five theoretical principles that follow from qualitative consideration of renal architecture and tubular permeabilities are proposed to explain the concentration of urine in the mammalian kidney. These are: 1) The medullary loop of the doubly folded S-shaped configuration of the nephron permits solute supplied by ascending Henle's limb (AHL) to extract water from descending Henle's limb (DHL) and collecting duct (CD). 2) The cortical loop allows the diluted AHL fluid to return to isotonicity with cortical plasma before returning to the medulla. 3) The folded vasa recta and surrounding interstitium (the central core) provide an expansion chamber for the performance of osmotic work and a mixing chamber for salt and urea. This mixing induces passive salt transport out of AHL. 4) Overall, the system acts as a solute cycling multiplier from the AHL to vascular core and the osmotically equilibrated DHL and CD. 5) The short-looped nephrons provide urea to drive salt transport out of AHL of long nephrons in the inner medulla.
 ...
PMID:The renal concentrating mechanism: fundamental theoretical concepts. 684 Feb 88

Reabsorption of glucose, salt and water was measured in 7-8 day pregnant and virgin rats by micropuncturing distal nephrons during saline and glucose infusions. Unidirectional fluxes of glucose were measured in loops of Henle and collecting ducts. There were no significant differences in single nephron glomerular filtration rate (S.N.G.F.R.) between virgin and pregnant animals during saline infusion. During glucose infusion S.N.G.F.R. was higher in pregnant animals than in virgins. There is no evidence of a failure of reabsorption of glucose by the proximal tubule in pregnant animals. More glucose is reabsorbed from the loop of Henle in virgin animals than in pregnant animals during saline infusion but during glucose infusion the converse is true. During both saline and glucose infusion there is less reabsorption of glucose from the collecting duct in pregnant animals than in virgin animals. It is concluded that the increased excretion of glucose during pregnancy can be attributed to alteration of glucose handling by distal segments of the nephron.
 ...
PMID:Glucose handling by distal portions of the nephron during pregnancy in the rat. 687 3

After adrenal enucleation rats have an impaired ability to excrete a salt load. From micropuncture studies comparing data obtained from the late distal collection site and the urine, it has been suggested that this antinatriuretic effect occurs along the collecting duct. These studies are indirect, however, and cannot evaluate the contribution of deep nephrons. We have performed studies directly measuring inner medullary collecting duct (IMCD) function in saline-loaded rats 6 days after adrenal enucleation (AE). The fraction of filtered fluid, sodium, chloride, and potassium was analyzed as a function of IMCD length. In six AE rats 35% of the fluid, 35% of the sodium, and 31% of the chloride delivered to the IMCD was reabsorbed. In six saline-loaded control rats, however, no statistically significant net reabsorption of fluid sodium, or chloride was detected. Net potassium secretion along the IMCD was found in both AE and control rats. No difference between groups was noted, and net addition accounted for 17% of the potassium excreted. We conclude that after AE, the excretion of fluid, sodium, and chloride is impaired during saline expansion because of enhanced reabsorption along the IMCD. AE does not affect potassium handling along the IMCD or potassium excretion.
 ...
PMID:Effect of adrenal enucleation on inner medullary collecting duct function in the rat. 708 34

1. The diffusional permeability of collecting ducts to 22Na+ and 36Cl- was measured in rat papillae in vitro. 2. The permeability of the collecting duct to 36Cl- was 0.72 (s.e.m. = 0.01; n = 356) microns/sec which was significantly higher than the value of 0.51 (s.e.m. = 0.01; n = 356) microns/sec measured for 22Na+. 3. Collecting ducts in papillae taken from rats on a high sodium intake had a 22Na+ permeability of 0.63 (s.e.m. = 0.04; n = 53) microns/sec which was significantly higher than the value on a normal salt intake (0.50, s.e.m. = 0.04; n = 46 microns/sec). 4. When papillae from normal rats were studied in plasma taken from salt loaded rats, the 22Na+ permeability of 0.59 (s.e.m. = 0.04; n = 18) microns/sec was significantly higher than when incubated in plasma from normal rats (0.44, s.e.m. = 0.05; n = 12) microns/sec. 5. An extract of urine with natriuretic activity had no effect on 22Na+ permeability when tested in this system. 6. Adrenalectomy, PGE2, indomethacin and antidiuretic hormone had no significant effect on 22Na+ and 36Cl- permeability. 7. A substance exists in plasma from salt loaded animals that increases the permeability of collecting ducts to sodium. This effect could explain the component of the natriuresis that follows saline infusion which is independent of changes in glomerular filtration rate, aldosterone, or proximal tubule reabsorption.
 ...
PMID:The permeability of collecting ducts to 22Na+ and 36Cl- in rat isolated papillae. 716 10

We examined the effects of cisplatin (5 mg/kg BW) on renal function in rats. Three days after administration of cisplatin whole kidney clearance of inulin fell and 24-h urine volume increased. Maximal urine osmolality and papillary solute content were reduced. Superficial nephron glomerular filtration rate measured along the proximal tubule, where no leak of inulin could be demonstrated, was reduced in cisplatin-treated animals. Differences between superficial nephron glomerular filtration rate determined in proximal and distal tubules were greater in cisplatin-treated rats than in control rats. Neither a change in fluid or sodium movement along superficial nephrons nor a reduced early distal tubule transepithelial sodium gradient explain the polyuria. Urea was reabsorbed from, not added to, the loop fluid in cisplatin-treated animals. Morphologic changes were evident in the S3 segment of the proximal tubule in cisplatin-treated animals but the glomeruli were normal. Polyuria occurred despite diminished glomerular filtration rate in cisplatin nephrotoxicity. The diminished concentration of salt and urea in the papilla as a result of abnormal function of the collecting duct or pars recta portion of the proximal tubule contributed to the defect in concentrating ability.
 ...
PMID:Cisplatin nephrotoxicity in rats: defect in papillary hypertonicity. 719 98

Collecting duct transport of fluid, sodium and potassium was studied in rats infused with Ringer solution (5 ml . 100 g body wt-1 . h-1). A terminal segment of surface collecting duct in the exposed papilla was catheterized as far upstream as possible under visual observation. After fluid sampling the same duct was punctured at the same site with a glass micropipette and a second sample was taken. Samples were then obtained from the opening of the duct at the papilla tip by both catheter and micropipette. No significant difference between the two collection sites was found in the fraction of filtered sodium, potassium, or fluid remaining in the tubules, independent of the sampling technique used, indicating that volume expansion inhibited salt and water reabsorption. Although fractional fluid and sodium remainders were slighlty higher and potassium remainder lower in upstream micropuncture samples compared to catheterization samples, the good correlation between collections obtained with both techniques suggests that both are equally valid as indicators of transport in terminal collecting ducts.
 ...
PMID:Comparison of micropuncture of microcatheterization in papillary collecting duct. 739 98

A histophysiological study was made of the kidney of Amphipnous cuchia subjected to different osmotic conditions (distilled water, 50% and 15% sodium chloride solution). These fish possess typical glomerular kidneys having nephrons composed of a glomerular body, neck segment, proximal convoluted segment (I & II), distal segment, and collecting duct system. When subjected to a hypotonic medium (distilled water) the fish show marked expansion in glomeruli resulting in 'glomerulitis'. A marked shrinkage in glomerular body tissue is found after 50% salt solution treatment and the fish die within one hour of immersion. Many pathological changes occur in the renal capsule and renal segment when the fish are treated with 15% salt solution. The glomerular bodies show shrinkage, degeneration and cyst formation. The glomerular shrinkage is probably due to constriction of arterioles which affects the filtration rate and thus protects against loss of water. Formation of cysts could be a protective device to save the glomeruli from degeneration. The renal tubules show hypertrophy, vacuolization, nuclear degeneration and cyst formation.
 ...
PMID:Structural changes in the kidney of freshwater mud eel Amphipnous cuchia (Ham.) subjected to different osmotic conditions. 744 47

Endogenous prostaglandin (PG) E2 production potently modulates salt and water transport in the kidney. Multiple direct effects of PGE2 on epithelial water and sodium transport have been demonstrated in the rabbit cortical collecting duct (CCD). Both functional and molecular studies now suggest that these disparate effects of PGE2 on CCD function are mediated by different EP receptors. When added in the presence of vasopressin, PGE2 inhibits cyclic AMP generation and water absorption. These effects are mediated via an inhibitory G-protein (Gi). In situ hybridization demonstrates high levels of expression of the Gi-coupled EP3 receptor in the rabbit collecting duct. However, by itself, PGE2 also stimulates cyclic AMP generation and water permeability. These effects appear to be mediated via a distinct EP receptor (possibly an EP4 receptor). PGE2 also increases intracellular Ca2+ in the CCD and inhibits Na+ absorption via a Ca(2+)-dependent mechanism. The EP1 receptor is postulated to be responsible for this action of PGE2. We suggest receptor-selective prostaglandin analogs may be used to selectively modulate sodium and water transport in the kidney.
 ...
PMID:Functional and molecular aspects of prostaglandin E receptors in the cortical collecting duct. 762 54

Prostaglandin E2 (PGE2) is the major renal cyclooxygenase metabolite of arachidonic acid. Urinary excretion of PGE2 is increased by dietary salt restriction, as well in cirrhosis and congestive heart failure. To determine whether urinary PGE2 affects transport along the nephron, the actions of luminal PGE2 were studied in the isolated perfused rabbit cortical collecting duct (CCD). Luminal PGE2 transiently hyperpolarized transepithelial voltage (Vt) in a dose-dependent manner (half-maximal effect approximately 10(-8) M) in contrast to a sustained depolarization of Vt produced by basolateral PGE2. Luminal PGE2 (0.1 microM) also significantly stimulated osmotic water permeability in the CCD. In CCDs cultured on semipermeable supports, apical PGE2 stimulated adenosine 3',5'-cyclic monophosphate (cAMP) production, suggesting the effects of luminal PGE2 are mediated by adenylyl cyclase-stimulating EP2 or EP4 receptors. Sulprostone, a PGE2 analogue selective for EP1 and EP3 receptors, affected Vt only when applied from the basolateral but not the luminal surface. Luminal application of the EP2 receptor agonist butaprost was also without effect. These results suggest that luminal PGE2 affects Vt via a butaprost-insensitive EP4 receptor. The Vt effect of luminal PGE2 was not blocked by pertussis toxin, also arguing against an EP3-mediated Gi-coupled effect. Finally, 1 microM luminal PGE2 only slightly increased CCD intracellular calcium concentration ([Ca2+]i), in contrast to the marked increase in [Ca2+]i produced by basolateral PGE2 (0.1 microM).(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Luminal prostaglandin E receptors regulate salt and water transport in rabbit cortical collecting duct. 765

In this paper we describe the effect of partitioning exchange of ascending thin limb (ATL) and collecting duct (CD) between a central vascular space (CORE) and a radially separated capillary node (NODE) in a mathematical model of the concentrating mechanism of the renal inner medulla. A detailed description of the model has been provided [J. L. Stephenson, J. F. Jen, H. Wang, and R. P. Tewarson. Am. J. Physiol. 268 (Renal Fluid Electrolyte Physiol. 37): F680-F692, 1995]. We define a partition coefficient theta, which denotes the fractional exchange of CD and ATL with the NODE. Thus with theta = 0 we have a central core model, in which the ATL and CD exchange with the CORE only, and with theta = 1 we have a totally radially separated model, in which the ATL and CD exchange with the NODE only. Decreasing the partition coefficient from 1 to 0 effects a continuous transition from a totally radially separated model to a central core model. As this transition progresses with increasing exchange with the CORE, the osmolalities in all structures become nearly the same at the papilla, and the ability to transport salt uphill is lost. This is true even with no radial diffusion. However, radial diffusion and direct exchange with the CORE act synergistically in decreasing osmolality differences at the papilla and the capacity for convective uphill transport. These are lost in a more or less parallel way. There is, however, no significant concomitant change in concentrating ability. These results indicate that models with radial mixing of the interstitial vascular space are probably reasonably good approximations for the inner medulla.
 ...
PMID:Comparison of central core and radially separated models of renal inner medulla. 773 26


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>