Dynamics of nucleotides in distal nephron of mice with nephrogenic diabetes insipidus

1986 ◽  
Vol 250 (1) ◽  
pp. F151-F158 ◽  
Author(s):  
E. Kusano ◽  
A. N. Yusufi ◽  
N. Murayama ◽  
J. Braun-Werness ◽  
T. P. Dousa
Keyword(s):  
Diabetes Insipidus ◽  
Nephrogenic Diabetes Insipidus ◽  
Fold Increase ◽  
Thick Ascending Limb ◽  
Camp Phosphodiesterase ◽  
Camp Content ◽  
Medullary Thick Ascending Limb ◽  
Atp Levels ◽  
Collecting Tubules ◽  
Camp Levels

In mice with hereditary nephrogenic diabetes insipidus (NDI), the high activity of cAMP-phosphodiesterase (cAMP-PDIE) in medullary collecting tubules (MCT) prevents the increase in cAMP content in response to vasopressin [Arg8]vasopressin (AVP). Even when the cAMP response to AVP is partly corrected by cAMP-PDIE inhibitor 1-methyl-3-isobutylxanthine (MIX), under all tested conditions the cAMP levels in MCT of NDI mice remained much lower than in controls (B. A. Jackson, R. M. Edwards, H. Valtin, and T. P. Dousa, J. Clin. Invest. 66: 110-122, 1980). In the present study, we explored which factors may account for this defect. We determined contents of ATP, nicotinamide adenine dinucleotide (NAD), and the levels of cAMP in MCT and in medullary thick ascending limb of Henle's loop (MAL) microdissected from control and NDI mice. In the presence of 1 microM AVP and 0.05 mM MIX, the cAMP levels accumulated in MCT of NDI mice were four times lower compared with controls, but the levels of ATP and NAD were not different. ATP levels in MAL of NDI mice were slightly (delta -23%) lower than in MAL from controls, and in distal convoluted tubules (DCT) of NDI mice the ATP levels were also decreased (delta -49%). Although AVP alone had little effect on cAMP levels in mouse MAL in the presence of 0.1 mM forskolin, the AVP elicited a 20-fold increase of cAMP of both the control and NDI mice. Addition of 0.1 mM forskolin further increased the cAMP accumulation in MCT incubated with AVP.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of cAMP-phosphodiesterase isozymes in pathogenesis of murine nephrogenic diabetes insipidus

1991 ◽  
Vol 261 (2) ◽  
pp. F345-F353 ◽  
Author(s):  
S. Homma ◽  
S. M. Gapstur ◽  
A. Coffey ◽  
H. Valtin ◽  
T. P. Dousa
Keyword(s):  
Diabetes Insipidus ◽  
Nephrogenic Diabetes Insipidus ◽  
Camp Phosphodiesterase ◽  
Pde Inhibitors ◽  
Collecting Ducts ◽  
Camp System ◽  
And Control ◽  
Camp Levels ◽  
Normal Controls

To test the hypothesis that rapid adenosine 3',5'-cyclic monophosphate (cAMP) catabolism via cyclic 3',5'-nucleotide phosphodiesterase (PDE) is a cause of the unresponsiveness to vasopressin (VP) in mice with hereditary nephrogenic diabetes insipidus (NDI), we investigated properties of PDEs and other aspects of the VP-dependent cAMP-signaling system in segments of collecting ducts [inner medullary (IMCD), cortical (CCD), and outer medullary (OMCD) ducts] microdissected from control mice and mice with NDI. The activity of cAMP-PDE, but not of cGMP-PDE, was markedly higher in IMCD (+109%), and to a lesser degree in OMCD (+41%) and CCD (+27%), of NDI mice than in normal controls. The cAMP-PDE in IMCD of NDI mice was more sensitive to inhibition by the PDE isozyme-specific inhibitors rolipram and cilostamide, but not by 3-isobutyl-1-methylxanthine, than was the cAMP-PDE in controls. Levels of cAMP in intact IMCD and CCD from NDI mice completely failed to increase in response to 10(-6) M VP. Incubation with rolipram alone, but not with cilostamide alone, restored VP-dependent cAMP accumulation in IMCD of NDI mice to the levels found in control mice; addition of cilostamide further enhanced the effect of rolipram. Analogous (but quantitatively lesser) anomalies of the VP-dependent cAMP system, including the effects of PDE inhibitors, were observed also in CCD of NDI mice. However, the activity of VP-stimulated adenylate cyclase assayed in permeabilized IMCD did not differ in NDI and control mice. These results indicate that anomalously high activities of low-Km cAMP-PDE isozymes account for the failure of collecting ducts of NDI mice to increase cAMP levels in response in VP.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals MON-LB65 Lithium: The Culprit of Multiple Endocrinopathies

2020 ◽  
Vol 4 (Supplement_1) ◽  
Author(s):  
Alice Yau ◽  
Gul Bahtiyar ◽  
Giovanna Rodriguez ◽  
Jose R Martinez Escudero
Keyword(s):  
Bipolar Disorder ◽  
Diabetes Insipidus ◽  
Mental Status ◽  
Nephrogenic Diabetes Insipidus ◽  
Kidney Injury ◽  
Urine Osmolality ◽  
Altered Mental Status ◽  
Clinical Findings ◽  
Volume Depletion ◽  
Collecting Tubules

Abstract Background: Lithium, commonly used to treat various psychiatric disorders such as bipolar disorder, can cause acute toxicity that presents with nausea, vomiting and diarrhea. Lithium can also cause life-threatening endocrine abnormalities, including hypercalcemia, hypernatremia, and both hypo- and hyperthyroidism. Clinical Case: A 61-year old female with hypothyroidism, bipolar disorder, hyperparathyroidism with two-gland parathyroidectomy on lithium for over 30 years presented with altered mental status. Initial labs revealed elevated creatinine 1.92 mg/dL (0.8-2.00mg/dL) compared to baseline 0.82 mg/dL, sodium 154 mg/dL (135-147 mg/dL), Corrected calcium 11.7 mg/dL (8.5-10.5 mg/dL), PTH 96 pg/mL (15-65 pg/mL), and high lithium levels 1.45 mmol/L (0.60-1.20 mmol/L). Further studies showed hypotonic polyuria with no increase in urine osmolality after desmopressin, consistent with nephrogenic diabetes insipidus. Lithium was held and she was treated with aggressive intravenous hydration with dextrose 5% water. Hypercalcemia is thought to result from increased secretion of PTH due to an increased set point at which calcium suppresses PTH release; this often resolves once lithium is stopped. Lithium can also unmask previously unrecognized mild hyperparathyroidism, and/or raise serum PTH concentrations independent of calcium levels.1 The drug interferes with the kidneys’ ability to concentrate urine in the collecting tubules by desensitizing response to antidiuretic hormone, causing diabetes insipidus. The resulting volume depletion from excessive urinary water loss in turn lead to acute kidney injury and hypernatremia.2 Hypothyroidism results from lithium-inhibited synthesis and release of thyroid hormones and decreases iodine trapping. Conclusion: Although these are infrequent complications of lithium use, they remain pertinent clinical findings to consider due to their morbidity. In this case, our patient may have avoided multiple chronic electrolyte abnormalities leading to altered mental status if lithium toxicity had been recognized earlier. References:1. García-Maldonado, Gerardo, and Rubén de Jesús Castro-García. “Endocrinological Disorders Related To The Medical Use Of Lithium. A Narrative Review”. Revista Colombiana De Psiquiatría (English Ed.), vol 48, no. 1, 2019, pp. 35-43. Elsevier BV, doi:10.1016/j.rcpeng.2018.12.005. 2. Tasci, E. “Lithium-Induced Nephrogenic Diabetes Insipidus Responsive To Desmopressin”. Acta Endocrinologica (Bucharest), vol 15, no. 2, 2019, pp. 270-271. ACTA Endocrinologica Foundation, doi:10.4183/aeb.2019.270.

Role of arginine vasopressin in medullary thick ascending limb on maximal urinary concentration

1986 ◽  
Vol 251 (2) ◽  
pp. F266-F270 ◽  
Author(s):  
J. K. Kim ◽  
S. N. Summer ◽  
A. E. Erickson ◽  
R. W. Schrier
Keyword(s):  
Adenylate Cyclase ◽  
Arginine Vasopressin ◽  
Urinary Concentration ◽  
Thick Ascending Limb ◽  
Sprague Dawley ◽  
Urinary Osmolality ◽  
Medullary Thick Ascending Limb ◽  
Sprague Dawley Rats ◽  
Collecting Tubules

Two groups of Sprague-Dawley rats, Harlan (H) and Charles River (CR), were discovered in that the medullary thick ascending limb (MAL) had a profoundly different adenylate cyclase response to arginine vasopressin (AVP). Using these two groups of rats, we studied the correlation between AVP action on the MAL and maximal urinary concentration. AVP (10(-6) M) significantly stimulated adenylate cyclase in MAL of H rats (7.4 +/- 0.9 to 43.8 +/- 4.6 fmol cAMP formed X 30 min-1 X mm-1, P less than 0.001) but not in CR rats (10.3 +/- 1.4 to 12.7 +/- 2.0 fmol cAMP formed X 30 min-1 X mm-1, NS). In contrast, AVP significantly stimulated adenylate cyclase of cortical, outer and inner medullary collecting tubules from both H and CR rats. Glucagon (10(-6) M) significantly stimulated adenylate cyclase of MAL from both H and CR rats. After 48 h of fluid deprivation, urinary osmolality was significantly higher (P less than 0.001) in the H (4,504 +/- 399 mosmol/kg H2O, n = 14) than CR (2,840 +/- 176 mosmol/kg H2O, n = rats. This observation was not attributable to differences in creatinine clearance (CR, 1.30 +/- 0.24; H, 1.24 +/- 0.03 ml/min, NS, n = 4) or plasma AVP (CR, 12.75 +/- 1.44; H, 12.38 +/- 1.17 pg/ml, NS, n = 6) levels. These results therefore suggest that the action of AVP on the MAL, in addition to the effect on collecting tubules, is involved in maximal urinary concentration in rats.

scholarly journals Differential regulation of NFAT5 by NKCC2 isoforms in medullary thick ascending limb (mTAL) cells

2011 ◽  
Vol 300 (4) ◽  
pp. F966-F975 ◽  
Author(s):  
Shoujin Hao ◽  
Hong Zhao ◽  
Zbigniew Darzynkiewicz ◽  
Sailaja Battula ◽  
Nicholas R. Ferreri
Keyword(s):  
Protein Expression ◽  
Laser Scanning ◽  
Transcriptional Activity ◽  
Primary Cultures ◽  
Fold Increase ◽  
Thick Ascending Limb ◽  
Activated T Cells ◽  
Mrna Accumulation ◽  
Medullary Thick Ascending Limb ◽  
Nacl Concentration

The effects of Na+-K+-2Cl− cotransporter type 2 (NKCC2) isoforms on the regulation of nuclear factor of activated T cells isoform 5 (NFAT5) were determined in mouse medullary thick ascending limb (mTAL) cells exposed to high NaCl concentration. Primary cultures of mTAL cells and freshly isolated mTAL tubules, both derived from the outer medulla (outer stripe>inner stripe), express NKCC2 isoforms A and F. The relative expression of NKCC2A mRNA was approximately twofold greater than NKCC2F in these preparations. The abundance of NKCC2A mRNA, but not NKCC2F mRNA, increased approximately twofold when mTAL cells were exposed for 2 h to a change in osmolality from 300 to 500 mosmol/kgH2O, produced with NaCl. Total NKCC2 protein expression also increased. Moreover, a 2.5-fold increase in NFAT5 mRNA accumulation was observed after cells were exposed to 500 mosmol/kgH2O for 4 h. Laser-scanning cytometry detected a twofold increase in endogenous NFAT5 protein expression in response to high NaCl concentration. Pretreatment with the loop diuretic bumetanide dramatically reduced transcriptional activity of the NFAT5-specific reporter construct TonE-Luc in mTAL cells exposed to high NaCl. Transient transfection of mTAL cells with shRNA vectors targeting NKCC2A prevented increases in NFAT5 mRNA abundance and protein expression and inhibited NFAT5 transcriptional activity in response to hypertonic stress. Silencing of NKCC2F mRNA did not affect NFAT5 mRNA accumulation but partially inhibited NFAT5 transcriptional activity. These findings suggest that NKCC2A and NKCC2F exhibit differential effects on NFAT5 expression and transcriptional activity in response to hypertonicity produced by high NaCl concentration.

Contiguous gene deletion in a Chinese family with X-linked nephrogenic diabetes insipidus: challenges in early diagnosis and implications for affected families

2019 ◽  
Vol 32 (8) ◽  
pp. 915-920
Author(s):  
Mei Tik Leung ◽  
Jacqueline K.K. Sit ◽  
Hoi Ning Cheung ◽  
Yan Ping Iu ◽  
Winnie K.Y. Chan ◽  
...  
Keyword(s):  
Genetic Analysis ◽  
Diabetes Insipidus ◽  
Nephrogenic Diabetes Insipidus ◽  
Failure To Thrive ◽  
Index Patient ◽  
Chinese Family ◽  
Molecular Testing ◽  
Carrier Status ◽  
Young Infants ◽  
Collecting Tubules

Abstract Nephrogenic diabetes insipidus (NDI) is a rare disorder of the renal collecting tubules, characterized by an inability to concentrate urine due to an impaired response to arginine vasopressin (AVP), resulting in dilute urine and polyuria. Causes of NDI are heterogeneous and diagnosing congenital NDI (cNDI) in young infants is clinically challenging, as typical symptoms are often unappreciated or inconspicuous. Instead, young infants may present with non-specific signs such as vomiting, poor feeding, failure to thrive, unexplained fevers, irritability, constipation or diarrhea. We report a 37-day-old infant who presented with polyuria and severe hypernatremic dehydration that was unresponsive to vasopressin. The patient was treated with amiloride, indomethacin and hydrochlorothiazide. Genetic analysis revealed a novel contiguous deletion involving the entire AVPR2 gene and the last exon of the adjacent ARHGAP4 gene. A study of the family confirmed the carrier status in the mother. This case illustrates the importance of molecular testing in confirming the diagnosis in the index patient, as well as in identifying asymptomatic at-risk female carriers so that appropriate genetic counselling can be given for reproductive planning. All pediatric patients with suspected cNDI should undergo genetic analysis for a definitive diagnosis.

Cellular action of arginine vasopressin in the isolated renal tubules of hypothyroid rats

1987 ◽  
Vol 253 (1) ◽  
pp. F104-F110 ◽  
Author(s):  
J. K. Kim ◽  
S. N. Summer ◽  
R. W. Schrier
Keyword(s):  
Adenylate Cyclase ◽  
Arginine Vasopressin ◽  
Morphological Changes ◽  
Renal Tubules ◽  
Thick Ascending Limb ◽  
Urinary Volume ◽  
Outer Medulla ◽  
Urinary Osmolality ◽  
Medullary Thick Ascending Limb ◽  
Collecting Tubules

Hypothyroidism has been demonstrated to be associated with an impaired concentrating capacity and specific morphological changes in the thick ascending limbs. This study was performed to evaluate the cellular action of arginine vasopressin (AVP) in the isolated renal tubules from control (C) and hypothyroid (HT) rats. Hypothyroidism was induced by feeding aminotriazole for 4 wk. Urinary volume was higher in HT rats (C 13.5 +/- 0.9, HT 17.7 +/- 0.9 ml/24 h, P less than 0.005) and urinary osmolality was lower in HT rats (C 1,707 +/- 49, HT 1,229 +/- 35 mosmol/kgH2O, P less than 0.001). Plasma AVP levels were significantly higher in HT rats (C 1.93 +/- 0.59, HT 4.12 +2- 0.62 pg/ml, P less than 0.05), thus documenting AVP resistance. The adenylate cyclase response to AVP (10(-6) M) was significantly lower (P less than 0.02) in the medullary thick ascending limb of Henle's loop (mTALH) in HT (14.3 +/- 2.4 to 41.7 +/- 5.8 fm X 30 min-1 X mm-1, P less than 0.001) than in mTALH in C rats (14.4 +/- 2.8 to 110.1 +/- 24.9 fm X 30 min-1 X mm-1, P less than 0.001). In contrast, the adenylate cyclase response to AVP was not significantly different in collecting tubules of cortex, outer medulla, and inner medulla from C and HT rats, although a slight decrease in response to AVP was observed in cortical and outer medullary collecting tubules.(ABSTRACT TRUNCATED AT 250 WORDS)

Cellular mechanism of lithium-induced nephrogenic diabetes insipidus in rats

1991 ◽  
Vol 261 (3) ◽  
pp. F505-F511 ◽  
Author(s):  
M. Yamaki ◽  
E. Kusano ◽  
T. Tetsuka ◽  
S. Takeda ◽  
S. Homma ◽  
...  
Keyword(s):  
Diabetes Insipidus ◽  
G Protein ◽  
Nephrogenic Diabetes Insipidus ◽  
Collecting Duct ◽  
Chronic Administration ◽  
Cellular Mechanism ◽  
Control Group ◽  
Dependent Manner ◽  
Camp Production ◽  
Camp Content

One of the mechanisms by which Li evokes polyuria is thought to be impairment of arginine vasopressin (AVP)-sensitive adenylate cyclase (AdC) in cells of the renal collecting duct. To investigate how AdC is influenced by chronic administration of Li, we created nephrogenic diabetes insipidus (NDI) in rats and microdissected the medullary collecting tubule from both control and NDI rats. In the NDI group, the 10(-6) M AVP-stimulated cAMP contents failed to increase completely, and the levels were significantly lower than that of the control group (10.4 +/- 1.4 vs. 48.4 +/- 4.7 fmol/mm, P less than 0.001). Pretreatment with pertussis toxin (PT), an inhibitor of inhibitory G protein (Gi), did not affect the basal cAMP levels in both groups, although it increased AVP-stimulated cAMP production in the NDI group in a dose- and time-dependent manner. AVP-stimulated cAMP production with over 100 ng/ml PT in the NDI group reached the levels observed in the control group. Incubation with cholera toxin, an agonist of stimulatory G protein (Gs), increased the cAMP content in the two groups to almost equal levels. To exclude the possibility that prostaglandin E2 (PGE2) is involved in the cellular mechanism of Li-induced NDI, the effect of indomethacin (Indo) on PT action was examined. However, Indo (10(-5) M) did not influence either the basal or AVP-dependent cAMP contents. From these results it is suggested that Li impairs AVP-sensitive AdC not through inhibition of Gs but through activation of Gi and that PGE2 may not be involved in the cellular pathogenesis of NDI at least in the rat at the step of cAMP formation.

scholarly journals Potential role of purinergic signaling in lithium-induced nephrogenic diabetes insipidus

2009 ◽  
Vol 296 (5) ◽  
pp. F1194-F1201 ◽  
Author(s):  
Yue Zhang ◽  
Raoul D. Nelson ◽  
Noel G. Carlson ◽  
Craig D. Kamerath ◽  
Donald E. Kohan ◽  
...  
Keyword(s):  
Diabetes Insipidus ◽  
Nephrogenic Diabetes Insipidus ◽  
Ex Vivo ◽  
Purinergic Signaling ◽  
Collecting Duct ◽  
Control Diet ◽  
Fold Increase ◽  
Extracellular Nucleotides ◽  
Confocal Laser ◽  
Sprague Dawley

Lithium (Li)-induced nephrogenic diabetes insipidus (NDI) has been attributed to the increased production of renal prostaglandin (PG)E2. Previously we reported that extracellular nucleotides (ATP/UTP), acting through P2y2 receptor in rat medullary collecting duct (mCD), produce and release PGE2. Hence we hypothesized that increased production of PGE2 in Li-induced NDI may be mediated by enhanced purinergic signaling in the mCD. Sprague-Dawley rats were fed either control or Li-added diet for 14 or 21 days. Li feeding resulted in marked polyuria and polydipsia associated with a decrease in aquaporin (AQP)2 protein abundance in inner medulla (∼20% of controls) and a twofold increase in urinary PGE2. When acutely challenged ex vivo with adenosine 5′- O-(3-thiotriphosphate) (ATPγS), UTP, or ADP, mCD of Li-fed rats showed significantly higher increases (50–130% over control diet-fed rats) in PGE2 production, indicating that more than one subtype of P2y receptor is involved. This was associated with a 3.4-fold increase in P2y4, but not P2y2, receptor mRNA expression in the inner medulla of Li-fed rats compared with control diet-fed rats. Confocal laser immunofluorescence microscopy revealed predominant localization of both P2y2 and P2y4 receptors in the mCD of control or Li diet-fed rats. Together, these data indicate that in Li-induced NDI 1) purinergic signaling in the mCD is sensitized with increased production of PGE2 and 2) P2y2 and/or P2y4 receptors may be involved in the enhanced purinergic signaling. Our study also reveals the potential beneficial effects of P2y receptor antagonists in the treatment and/or prevention of Li-induced NDI.

Calcitonin gene-related peptide: effects on renal arteriolar tone and tubular cAMP levels

1990 ◽  
Vol 258 (1) ◽  
pp. F121-F125 ◽  
Author(s):  
R. M. Edwards ◽  
W. Trizna
Keyword(s):  
Calcitonin Gene Related Peptide ◽  
Rabbit Kidney ◽  
Thick Ascending Limb ◽  
Camp Accumulation ◽  
Related Peptide ◽  
Medullary Thick Ascending Limb ◽  
Calcitonin Gene ◽  
Afferent Arterioles ◽  
Arteriolar Tone ◽  
Camp Levels

The effects of calcitonin gene-related peptide (CGRP) and salmon calcitonin (SCT) on isolated afferent and efferent arteriolar tone and on adenosine 3',5'-cyclic monophosphate (cAMP) accumulation in isolated tubules from rabbit kidney were compared. By themselves, CGRP and SCT had no effect on arteriole diameter. In norepinephrine-contracted afferent arterioles, CGRP, but not SCT, produced a concentration-dependent relaxation [50% maximal dose, (EC50) = 1.3 nM]. In contrast, neither CGRP nor SCT had any effect on efferent arterioles precontracted with norepinephrine or angiotensin II. CGRP, but not SCT, stimulated cAMP accumulation in glomeruli (EC50 = 0.5 nM). In tubules, CGRP increased cAMP levels only in SCT-responsive segments, e.g., cortical and medullary thick ascending limbs and distal convoluted tubules. In the medullary thick ascending limb, CGRP was approximately 500-fold less potent than SCT in stimulating cAMP accumulation with EC50s of 0.22 microM and 0.41 nM, respectively. The effect of maximum concentrations (1 microM) of CGRP and SCT on cAMP levels in the medullary thick ascending limb were not additive. The results suggest that there are specific CGRP receptors on afferent arterioles that produce relaxation and in glomeruli that are associated with an increase in cAMP production. In tubules, CGRP appears to be a weak agonist at the SCT receptor. We conclude that CGRP may play a role in the regulation of renal hemodynamics.

scholarly journals Treating lithium-induced nephrogenic diabetes insipidus with a COX-2 inhibitor improves polyuria via upregulation of AQP2 and NKCC2

2008 ◽  
Vol 294 (4) ◽  
pp. F702-F709 ◽  
Author(s):  
Gheun-Ho Kim ◽  
Nak Won Choi ◽  
Ju-Young Jung ◽  
Ji-Hyun Song ◽  
Chang Hwa Lee ◽  
...  
Keyword(s):  
Diabetes Insipidus ◽  
Nephrogenic Diabetes Insipidus ◽  
Collecting Duct ◽  
Urine Osmolality ◽  
Urinary Concentration ◽  
Prostaglandin E ◽  
Thick Ascending Limb ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Cox 2

Prostaglandin E2 may antagonize vasopressin-stimulated salt absorption in the thick ascending limb and water absorption in the collecting duct. Blockade of prostaglandin E2 synthesis by nonsteroidal anti-inflammatory drugs (NSAIDs) enhances urinary concentration, and these agents have antidiuretic effects in patients with nephrogenic diabetes insipidus (NDI) of different etiologies. Because renal prostaglandins are derived largely from cyclooxygenase-2 (COX-2), we hypothesized that treatment of NDI with a COX-2 inhibitor may relieve polyuria through increased expression of Na-K-2Cl cotransporter type 2 (NKCC2) in the thick ascending limb and aquaporin-2 (AQP2) in the collecting duct. To test this hypothesis, semiquantitative immunoblotting and immunohistochemistry were carried out from the kidneys of lithium-induced NDI rats with and without COX-2 inhibition. After male Sprague-Dawley rats were fed an LiCl-containing rat diet for 3 wk, the rats were randomly divided into control and experimental groups. The COX-2 inhibitor DFU (40 mg·kg−1·day−1) was orally administered to the experimental rats for an additional week. Treatment with the COX-2 inhibitor significantly relieved polyuria and raised urine osmolality. Semiquantitative immunoblotting using whole-kidney homogenates revealed that COX-2 inhibition caused significant increases in the abundance of AQP2 and NKCC2. Immunohistochemistry for AQP2 and NKCC2 confirmed the effects of COX-2 inhibition in lithium-induced NDI rats. The upregulation of AQP2 and NKCC2 in response to the COX-2 inhibitor may underlie the therapeutic mechanisms by which NSAIDs enhance antidiuresis in patients with NDI.

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