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)

The ontogenesis of vasopressin receptors in the rat collecting duct was studied by measuring the binding of [1-(beta-mercapto-beta,beta-cyclopentamethylenepropionic acid),2-O-methyltyrosine,4-threonine,8-ornithine,9-125I-tyrosylamide+ ++]-vasotocin (125I-d(CH2)5[Tyr(Me)2,Thr4,Tyr-NH(9)2]-OVT) to isolated cortical collecting ducts (CCD), outer medullary collecting ducts (OMCD) and inner medullary collecting ducts (IMCD) microdissected from collagenase-treated kidneys of 2- to 34-day-old rats and adult animals. The stereospecificity for recognition of a series of seven vasopressin structural analogues by CCD and OMCD receptors reveals that the labeled binding sites identified in 11- to 16-day-old and adult rats are homologous respectively and contain a major population of V2 type and a minor population of V1a type of vasopressin receptors. At all postnatal stages examined, the receptor density (expressed as 10(-18) mol radioligand bound per square millimeter tubular outer surface area) decreases gradually from the CCD to the IMCD. For the three segments, the numbers of receptors detected remained constant during the first 2 weeks after birth and increased sharply after 20 days to reach the corresponding adult levels during the fifth week.
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PMID:Postnatal ontogenesis of vasopressin receptors in the rat collecting duct. 138 71

Hydrolysis of arginine into urea and ornithine (Orn) was observed to take place in several segments of the rat nephron including cortical and medullary pars recta of the proximal tubule (PST) and collecting duct (CD). This work was now extended to the adult mouse and rabbit. Representative nephron segments, obtained by microdissection of collagenase-treated kidneys, were incubated with L-[guanido-14C]arginine (216 microM). Addition of urease produced 14CO2 + 2 NH3 from the newly formed urea released in the incubate. 14CO2 was trapped in KOH and counted. In both species, as well as in the rat, the PST was the site of the highest urea + Orn production, with an intensity increasing from cortex to medulla. For other nephron segments, the pattern was not similar in all species. Significant production of urea + Orn was observed in the proximal convoluted tubule and the medullary thick ascending limb in the rabbit, but not in the CD of either the rabbit or the mouse. The functional significance of this urea + Orn production remains unclear. The total amount of urea generated intrarenally by this reaction does not seem sufficient to play a significant role in the urinary concentrating mechanism. It may be assumed that Orn could be further metabolized to polyamines and play a role in maintaining cell integrity and function in the PST, especially in its medullary part, exposed to hypertonicity and poor oxygen supply.
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PMID:Localization of urea and ornithine production along mouse and rabbit nephrons: functional significance. 144 76

Two types of K+ channels, low conductance (28 pS) and intermediate conductance (85 pS), have been previously identified in the basolateral membrane of the cortical collecting duct (CCD) of the rat kidney (31, 32). In the present study, we used the patch-clamp technique to explore further the mechanism by which the low-conductance K+ channel is regulated. The conductance of the low-conductance K+ channel is inward rectifying, with an inward slope conductance of 30 pS between 0 and -20 mV and an outward slope conductance of 16 pS between 0 and 50 mV in symmetrical 140 mM KCl in the bath and in the pipette. This K+ channel was not sensitive to ATP (10 mM), tetraethylammonium chloride (5 mM), and quinidine (1 mM). Addition of 100 microM N omega-nitro-L-arginine methyl ester (L-NAME) or N omega-(imonoethyl)-L-ornithine (L-NIO), an inhibitor of nitric oxide synthase (NOS), completely blocked channel activity in cell-attached patches. In contrast, addition of 200 microM-D-NAME, which does not block NOS, had no effect on channel activity. The inhibitory effect of L-NAME or L-NIO was fully reversible and completely overcome by addition of exogenous nitric oxide (NO) donors, such as 10 microM S-nitroso-N-acetyl-penicillamine or sodium nitroprusside. Furthermore, addition of 100 microM 8-bromoguanosine 3',5'-cyclic monophosphate (8-BrcGMP) restored the activity of the channel when it had been inhibited by either L-NAME or L-NIO, indicating that the effect of NO on the channel activity was mediated by a cGMP-dependent pathway. In conclusion, NO plays a key role in the regulation of the basolateral 30-pS K+ channel and the effect of NO on channel activity is mediated by a cGMP-dependent pathway.
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PMID:Nitric oxide regulates the low-conductance K+ channel in basolateral membrane of cortical collecting duct. 896 33

Previous work from our laboratory has demonstrated that the inner medullary collecting duct (IMCD) expresses a large amount of nitric oxide synthase (NOS) activity. The present study was designed to characterize the transport of NOS substrate, L-arginine, in a suspension of bulk-isolated IMCD cells from the Sprague-Dawley rat kidney. Biochemical transport studies demonstrated an L-arginine transport system in IMCD cells that was saturable and Na(+) independent (n = 6). L-Arginine uptake by IMCD cells was inhibited by the cationic amino acids L-lysine, L-homoarginine, and L-ornithine (10 mmol/l each) and unaffected by the neutral amino acids L-leucine, L-serine, and L-glutamine. Both L-ornithine (n = 6) and L-lysine (n = 6) inhibited NOS enzymatic activity in a dose-dependent manner in IMCD cells, supporting the important role of L-arginine transport for NO production by this tubular segment. Furthermore, RT-PCR of microdissected IMCD confirmed the presence of cationic amino acid transporter CAT1 mRNA, whereas CAT2A, CAT2B, and CAT3 were not detected. These results indicate that L-arginine uptake by IMCD cells occurs via system y(+), is encoded by CAT1, and may participate in the regulation of NO production in this renal segment.
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PMID:Characterization of L-arginine transporters in rat renal inner medullary collecting duct. 1084 17

Previous studies have indicated that NO synthesis in isolated inner medullary collecting duct cells is reduced by cationic amino acids that compete with L-arginine for cellular uptake. In the present study, we investigated the effects of chronic renal medullary infusion of cationic amino acids on renal NO concentration and mean arterial pressure (MAP) in Sprague-Dawley rats. Renal medullary infusion of L-ornithine (50 microg/kg per min) or L-lysine (50 microg/kg per min) markedly decreased NO in the medulla (vehicle, 124 +/- 11 nmol/L; L-ornithine, 45 +/- 4 nmol/L; L-lysine, 42 +/- 6 nmol/L) and increased MAP (vehicle, 111 +/- 7 mm Hg; L-ornithine, 143 +/- 6 mm Hg; L-lysine, 148 +/- 3 mm Hg) after 5 days of infusion. In contrast, intravenous infusion of the same dose of L-ornithine or L-lysine for 5 days increased plasma concentration to levels similar to those observed with intramedullary infusion but did not change NO in the medulla or alter MAP. Furthermore, the NO-suppressing and hypertensive effects of medullary interstitial infusion of L-ornithine (50 microg/kg per min) were attenuated by simultaneous infusion of L-arginine (500 microg/kg per min; NO, 97 +/- 10 nmol/L; MAP, 124 +/- 3 mm Hg). A 5-day infusion of an antisense oligonucleotide against CAT-1 (18-mer, 8.3 nmol/h) significantly decreased CAT-1 protein in the medulla, decreased NO in the medulla (scrambled oligo, 124 +/- 10 nmol/L; antisense oligo, 67 +/- 11 nmol/L), and increased MAP (scrambled oligo, 113 +/- 2 mm Hg; antisense oligo, 130 +/- 2 mm Hg). These results suggest that uptake of L-arginine by cationic amino acid transport systems in the renal medulla plays an important role in the regulation of medullary NO and MAP in rats.
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PMID:Cationic amino acid transport in the renal medulla and blood pressure regulation. 1184 99