Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01185 (vasopressin)
 23,126 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tamm-Horsfall protein (THP), a normal constituent of mammalian urine, has been determined in rat urine under various conditions in an attempt to elucidate the physiological role of this glycoprotein. Experiments were designed to assess whether THP production is related to the process of urine concentration or to the transport activity of the thick ascending limb of the loop of Henle (TAL), the nephron segment where it is produced. For this purpose, THP excretion was measured, by radioimmunoassay, in adult male rats under 4 different conditions induced by the following chronic treatments: (1) furosemide (12 mg/day in osmotic minipumps); (2) increased water intake; (3) antidiuretic hormone (ADH) infusion (50 ng DDAVP/day in osmotic minipumps) in rats of the Brattleboro strain with hereditary hypothalamic diabetes insipidus; (4) high-protein (32% casein) versus low-protein diet (10% casein). Each experiment included 6 experimental and 6 control rats. After treatment for 1-3 weeks, 24-h urines were collected for determination of urine flow rate, osmolality, and creatinine and THP concentrations. No significant changes in THP excretion were observed in experiments (1) and (2) despite 5- to 7-fold-differences in urine flow rate. Antidiuretic hormone treatment in (3) slightly lowered THP excretion (287 +/- 53 vs. 367 +/- 41 micrograms/day per 100 g body weight; p less than 0.005), whereas high-protein diet, in experiment (4), led to a 50% increase in THP excretion (446 +/- 57 vs. 304 +/- 79 micrograms/day per 100 g body weight; p less than 0.001). Expressing THP excretion relative to that of creatine did not change these findings. These results show (1) that chronically established changes in the level of diuresis, chronic furosemide-induced blockade of the Na,K,Cl-cotransporter or the absence of ADH in Brattleboro rats have little or no impact on the level of THP production, and (2) that THP production is independent of the intensity of transport in the TAL, since two conditions which both are known to increase the transport rate of solutes in the TAL (ADH infusion and high-protein diet), resulted in opposite changes in THP excretion. It is concluded that the rate of THP synthesis is neither linked to the process of urine concentration nor to the ion transport activity of the TAL.
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PMID:Tamm-Horsfall protein excretion during chronic alterations in urinary concentration and protein intake in the rat. 172 Feb 54

This paper describes a rapid and simple method for isolation of medullary thick ascending limbs (MTAL) from rat kidney. The technique takes advantage of the fact that MTAL represents a high fraction of the inner stripe (IS) tissue in the outer medulla, and that this nephron segment is more resistant than others to mechanical and enzymatic disruption. Special attention was given in the design of each step of the isolation procedure in order to improve purity and yield of the preparation. Major steps are the following: careful dissection of the IS; cutting IS tissue into small pieces of regular size (approximately equal to 1 mm3); mild and brief enzymatic hydrolysis in a 65 U/ml collagenase solution; separation of long MTAL segments from other tubule fragments and cells, and washing of the collagenase solution, on a nylon sieve (100 microns opening). This technique does not require lengthy centrifugations and provides about 6 mg fresh tissue (= 1 mg protein) from two rat kidneys in 2 h. Light microscopy and transmission electron microscopy show a good purity (at least 95%) and good preservation of TAL ultrastructural morphology. Adenylate cyclase responsiveness to arginine-vasopressin (AVP), glucagon (GLU) and salmon calcitonin (SCT) of the MTAL suspension is similar to that reported for single microdissected rat MTAL. Viability of the MTALs was demonstrated by the ability to accumulate cyclic AMP in presence of AVP, GLU, SCT and forskolin. Normal oxygen consumption was 45.1 +/- 2.4 (SEM) microliter . mg protein-1 . h-1 (n = 8).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Quick isolation of rat medullary thick ascending limbs. Enzymatic and metabolic characterization. 301 64

We showed previously that increasing Ca2+ concentration in the incubation medium suppressed cAMP production in response to vasopressin (AVP), glucagon or forskolin in the medullary thick ascending limb of Henle (MTAL) but not in medullary collecting tubules of mouse kidney. In the present study, we examined, using nephron segments dissected from mouse kidney, whether the inhibitory effect of high Ca2+ is specific to MTAL. Increasing Ca2+ in the incubation medium from 1 to 5 mM inhibited cAMP production in response to parathyroid hormone (PTH), calcitonin, AVP or glucagon in cortical thick ascending limbs of Henle (CTAL), but dit not inhibit cAMP production stimulated by PTH or calcitonin in proximal convoluted tubules and that by AVP in cortical collecting tubules. In CTAL, high ambient Ca2+ also inhibited cAMP production stimulated by forskolin. Thus, our present data show that high Ca2+ inhibits cAMP production specifically in thick ascending limbs of Henle but not in the other nephron segments. High ambients Ca2+ may inhibit adenylate cyclase at postreceptor site(s) one of which may be the catalytic unit of the enzyme in TAL.
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PMID:High Ca2+ inhibits peptide hormone-dependent cAMP production specifically in thick ascending limbs of Henle. 302 19

This paper considers the quantitative interplay of various factors in modulating diluting power of in vitro medullary and cortical thick ascending limbs of Henle (MTAL and CTAL, respectively) segments from mouse and rabbit. Experimentally, the measured diluting power of the in vitro rabbit CTAL is greater than that of the rabbit MTAL, although the inherent rate of net Cl- absorption at high perfusion rates is considerably greater in the rabbit MTAL than in the rabbit CTAL. Similar results apply when comparing the rabbit CTAL to the mouse MTAL exposed to antidiuretic hormone (ADH). Our calculations show that, in the rabbit CTAL, the measured static head luminal salt concentration can be accounted for quantitatively by the measured rate of net salt absorption at a high perfusion rate together with the passive permeability coefficients for Na+ and Cl-. Moreover, with perfusion rates of 10% of single-nephron glomerular filtration rate, the transport properties of the CTAL predict that, at the end of the CTAL, the static head luminal Cl- concentration occurs if the initial perfusate contains either 50 or 150 mM Cl-. Thus one can argue that, in vivo the CTAL may be the cardinal determinant of the TAL contribution to diluting power and to external salt balance. The relatively blunted diluting power of in vitro MTAL segments can be accounted for quantitatively by assuming that luminal dilution, and the attendant osmotic gradient from lumen to cell, suppresses the inherent rate of transcellular Cl- transport. Our calculations also show that prostaglandin E2 and peritubular osmolality increases blunt tubular diluting power. Thus in vivo, the MTAL segment may be the cardinal determinant of TAL contribution to concentrating power and to intrarenal salt balance.
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PMID:Diluting power of thick limbs of Henle. III. Modulation of in vitro diluting power. 320 79

We recently cloned extracellular Ca(2+)-sensing receptors (CaRs) from bovine parathyroid and rat kidney that play key roles in Ca2+ homeostasis. Inactivating mutations of the CaR in the inherited human disorder, familial hypocalciuric hypercalcemia, cause reduced responsiveness of the parathyroid to extracellular Ca2+ (Cao2+), as well as abnormally avid renal tubular reabsorption of both Ca2+ and Mg2+ in the distal tubule, suggesting an important role for the CaR in regulating parathyroid hormone (PTH) secretion and renal handling of divalent cations. High Cao2+ also inhibits vasopressinstimulated adenosine 3',5'-cyclic monophosphate accumulation in the medullary thick ascending limb (MTAL) and water reabsorption in the collecting duct (CD) and modulates various other aspects of renal function. The relevance of the CaR to these processes, however, is uncertain. Reduced responsiveness of vasopressin-and PTH-mediated actions on the kidney have been described in the newborn that could potentially reflect effects of the CaR on these aspects of renal function. To define further the role of the CaR in regulating renal function, including the above-mentioned changes during the perinatal period, therefore, we have studied its ontogeny in rat kidney. Northern and Western blot analyses, as well as immunohistochemistry with CaR-specific probes, demonstrate that there is little prenatal expression of the extracellular Ca(2+)-sensing receptor, except in large tubules and branching ureteric buds of developing nephrons. Postnatally, CaR mRNA and protein increase markedly during the 1st wk, related principally to expression of the receptor in the developing TAL and, to a lesser extent, in the CD. The level of expression of the receptor remains nearly constant after postnatal day 14. These results demonstrate that the perinatal increases in expression of CaR mRNA and protein parallel its tissue-specific renal expression. Furthermore, it is possible that some of the previously described changes in renal handling of divalent cations and water in the perinatal and immediate postnatal period are related, in part, to the increasing levels of expression of the CaR and resultant inhibitory effects on the actions of PTH and antidiuretic hormone on the developing nephron.
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PMID:Ontogeny of the extracellular calcium-sensing receptor in rat kidney. 885 37

Liver cirrhosis is a chronic disease associated with sodium retention due to increased tubular sodium reabsorption. However, the exact tubular site of increased sodium reabsorption in uncertain. We have recently demonstrated selective hypertrophy of the inner stripe of the outer medulla (ISOM) in rats with liver cirrhosis induced by common bile duct ligation (CBL). The present study was designed in order to measure Na-K-ATPase activity in the two major tubular segments located in the ISOM: the thick ascending limb of henles (MTAL) and the collecting ducts (OMCD) in CBL rats. Sham-operated rats were used as controls. In addition, the natriuretic response to amiloride (0.2 mg kg(-1) h(-1) i.v) was examined in conscious, chronically instrumented rats during conditions where amiloride-induced volume losses were replaced continuously using a servo-controlled i.v. volume replacement system. For 4-5 weeks after CBL, cirrhotic rats showed sodium retention relative to control rats without any sign of ascites. Plasma levels of sodium and aldosterone were normal, but plasma vasopressin was increased. Effective renal plasma flow was significantly increased, whereas glomerular filtration rate (GFR) and renal lithium handling were normal. The CBL rats showed a blunted natriuretic response to amiloride (DeltaFE(Na): 1.17 +/- 0.15% vs. 1.65 +/- 0.13%; P < 0.05). In rats with CBL, Na-K-ATPase activity per mm tubular length was decreased in the OMCD and unchanged in the TAL segment. These results suggest that increased tubular sodium reabsorption in liver cirrhotic rats with early sodium retention is localized in segments proximal to the collecting ducts.
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PMID:Collecting duct function in liver cirrhotic rats with early sodium retention. 1210 Mar 63

The kidney plays an essential role in blood pressure regulation by controlling short-term and long-term NaCl and water balance. The thick ascending limb of the loop of Henle (TAL) reabsorbs 25-30% of the NaCl filtered by the glomeruli in a process mediated by the apical Na(+)-K(+)-2Cl(-) cotransporter NKCC2, which allows Na(+) and Cl(-) entry from the tubule lumen into TAL cells. In humans, mutations in the gene coding for NKCC2 result in decreased or absent activity characterized by severe salt and volume loss and decreased blood pressure (Bartter syndrome type 1). Opposite to Bartter's syndrome, enhanced NaCl absorption by the TAL is associated with human hypertension and animal models of salt-sensitive hypertension. TAL NaCl reabsorption is subject to exquisite control by hormones like vasopressin, parathyroid, glucagon, and adrenergic agonists (epinephrine and norepinephrine) that stimulate NaCl reabsorption. Atrial natriuretic peptides or autacoids like nitric oxide and prostaglandins inhibit NaCl reabsorption, promoting salt excretion. In general, the mechanism by which hormones control NaCl reabsorption is mediated directly or indirectly by altering the activity of NKCC2 in the TAL. Despite the importance of NKCC2 in renal physiology, the molecular mechanisms by which hormones, autacoids, physical factors, and intracellular ions regulate NKCC2 activity are largely unknown. During the last 5 years, it has become apparent that at least three molecular mechanisms determine NKCC2 activity. As such, membrane trafficking, phosphorylation, and protein-protein interactions have recently been described in TALs and heterologous expression systems as mechanisms that modulate NKCC2 activity. The focus of this review is to summarize recent data regarding NKCC2 regulation and discuss their potential implications in physiological control of TAL function, renal physiology, and blood pressure regulation.
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PMID:Molecular regulation of NKCC2 in the thick ascending limb. 2190 Apr 58