Patients with moderate to severe degrees of Henoch-Schonlein purpura (HSP) nephritis receive high-dose intravenous methylprednisolone pulse therapy (IMPT). Although the regimen is generally safe and effective, various complications occasionally develop. administration of excessive corticosteroid can induce urinary potassium wasting leading to hypokalemia. Polyuria, one of the complications of hypokalemia, is related to both increased thirst and mild nephrogenic diabetes insipidus. And hypokalemia itself also impairs the maximal renal urinary concentration ability. Although polyuria or nocturia after IMPT is not common, it is correctable immediately by oral potassium supplementation. Therefore, during IMPT, careful history taking of nocturia as well as monitoring urine volume, serum and urine potassium level at regular follow-up are necessary because even mild hypokalemia can provoke urine concentrating ability defect. We experienced a case of 11 year-old boy with HSP nephritis who suffered from hypokalemia-induced polyuria with nocturia right after IMPT.
Attention ; Diabetes Insipidus, Nephrogenic ; Humans ; Hypokalemia ; Kidney Concentrating Ability ; Methylprednisolone ; Nephritis ; Nocturia ; Polyuria ; Potassium ; Purpura, Schoenlein-Henoch ; Thirst

PURPOSE: The aquaporins (AQPs) are transmembrane water channel proteins. It is well known that AQP2, -3 and -4 contribute to the urinary concentration in collecting duct (CD) and also reported the presence of these three AQPs in the connecting tubule (CNT). Newborn rats are not capable of producing a concentrated urine. Rats develop the ability to concentrate urine after birth. The purpose of this study was to establish the time of the expression and the distribution of AQP2, -3 and -4 in the developing rat kidney. MATERIALS AND METHODS: Sprague-Dawley rats were used in all experiments. Kidneys were obtained from 16, 18 and 20-day-old fetuses and 1, 4, 7, 14 and 21-day-old pups and preserved and processed for immunohistochemical studies using a preembedding immunoperoxidase procedure. AQP2, -3 and -4 immunoreactivity was detected using rabbit polyclonal antibody and donkey anti-rabbit IgG. RESULTS: AQP2, -3 and -4 appeared first in 16-day-old fetuses in the CD and in 18-day-old fetuses in the CNT. Immunoreactivity for AQP2, -3 and -4 was markedly increased after birth and gradually increased during development. In CNT cells and principal cells, AQP2, -3 and -4 were not distinctly demonstrated on the apical, lateral and basal plasma membrane respectively until 21 days after birth. Distinct polarity of these AQPs both in CNTcells and principal cells were observed at 21 days after birth. CONCLUSIONS: AQP2 -3, and -4 were expressed not only in CD but also in CNT before developing of urine concentrating ability during development and it is concluded that their expression and distribution in CNT may play a role in the development of urine concentration abilities in rat kidney.
Animals ; Aquaporin 2* ; Aquaporins ; Attention ; Cell Membrane ; Equidae ; Fetus ; Humans ; Immunoglobulin G ; Infant, Newborn ; Kidney Concentrating Ability ; Kidney Tubules ; Kidney* ; Parturition ; Rats* ; Rats, Sprague-Dawley

This study was undertaken to determine whether verapamil protects renal function in rabbits with ischemic acute renal failure. Renal ischemia was induced by clamping bilateral renal arteries for 60 min. One group received intravenously an infusion of verapamil (lmg/kg) for 30 min prior to initiation of renal artery clamping and the other group received equal volume of saline. Renal blood flow was measured with flowmeter before (basal) and 24 hr after ischemia. Serum creatinine level increased 24 hr after ischemia and remained high to 72 hr. When verapamil was pretreated, the level 48 and 72 hr after ischemia was significantly decreased compared with saline insusion. Urine flow was markedly decreased 24 hr after ischemia and remained depressed to 72 hr, but it was significantly increased 72 hr after ischemia in verapa- mil-pretreatment animals as compared with the saline-infusion animals. GFR were markedly reduced 24 hr after ischemia and remained depressed to 72 hr, which was significantly prevented by verapamil pretreatment. Ischemia caused a significant increase in FEVa and a reduction in Uosm, and TcH2O, indicating impairment in urine concentrating ability of tubules, and the impairment was significantly attenuated by verapamil. The uptake of p-aminohippurate in cortical slices was depressed by ischemia, which was significantly prevented by verapamil pretreatment. In salineinfusion animals, renal blood flow was not significantly different between the basal value and that after 24 hr of reflow. Renal blood flow was not significantly altered by verapamil pretreatment. Anoxia/reoxygenation injury in the control renal slices was not significantly prevented by Ca channel blockers. These results suggest that verapamil exerts a protective effect in ichemic acute renal failure, and the beneficial effects may be attributed to effects other than vasodilation. These data also indicate that a reduction in GFR following ischemia does not result from change in renal blood flow.
Acute Kidney Injury* ; Animals ; Constriction ; Creatinine ; Flowmeters ; Ischemia ; Kidney Concentrating Ability ; p-Aminohippuric Acid ; Rabbits* ; Renal Artery ; Renal Circulation ; Vasodilation ; Verapamil*

BACKGROUND: Thiazides have been used in nephrogenic diabetes insipidus (NDI) patients to decrease urine volume, but the mechanism of antidiuretic effect is not known yet. Recently, it has been demonstrated that abundance of aquaporin-2 (AQP2) was decreased in lithium induced NDI. We performed this study to investigate the effect of hydrochlorothiazide (HCTZ) in lithium induced NDI rats and the change of AQP2 expression. METHODS: NDI was induced in 7 male Spraque- Dawley rats by feeding lithium carbonate containing rat chow (40 mmol/kg) for 5 weeks. 4 rats were control group. HCTZ 3.75 mg/day (n=3 among lithium treated; Li+TZ) or vehicle (n=4 among lithium treated and control; Li and Control, respectively) was infused to the rats through osmotic minipump for the last 7 days. Urine volume and urine osmolality were measured. Kidneys were processed for immunohistochemistry and immunoblotting using antibody to AQP2. RESULTS: Li+TZ showed decreased urine volume (46+/-11 mL/day for Li+TZ vs. 127+/-1 mL/day for Li, p<0.05) and higher urine osmolality (557+/-139 mmol/kgH2O for Li+TZ vs. 207+/-9 mmol/kgH2O for Li, p<0.05) comparing to Li. In semi-quantitative immunoblotting using whole kidney homogenate, Li+TZ showed increase in AQP2 expression comparing to Li (39+/-2% for Li+TZ vs. 20+/-9% for Li, p<0.05, % of normal controls). In immunohistochemistry, AQP2 expression in cortex was markedly decreased after lithium treatment. But, AQP2 expression was slightly increased after HCTZ treatment. CONCLUSION: HCTZ treatment partially increased urine concentrating ability and AQP2 expression in rats with lithium induced NDI. We concluded that partial improvement in urine concentrating ability might be associated with upregulation of AQP2.
Animals ; Antidiuretic Agents ; Aquaporin 2* ; Diabetes Insipidus, Nephrogenic* ; Humans ; Hydrochlorothiazide* ; Immunoblotting ; Immunohistochemistry ; Kidney ; Kidney Concentrating Ability ; Lithium Carbonate ; Lithium* ; Male ; Osmolar Concentration ; Rats* ; Thiazides ; Up-Regulation

BACKGROUND: Obstruction of urinary tract is common cause of renal disfunction. Recent discovery of aquaporin water channels expressed in the kidney and various organs has faciliated our understanding of water transport across the permeable epithelial cell membrane. This study was performed to investigate the effects of bilateral ureteral obstruction on renal expression and cellular distribution of these water channels in rat kidney. METHODS: Male Sprague-Dawley rats were divided two groups. The abdominal cavity was opened and 2-0 silk ligatures were proximally placed on both ureters in experimental group. Sham-operated group was treated in the same procedures except ligation. After closure of the abdomen, the animals were maintained for 48 hr while being given food and water ad libitum. Kidney sections of both groups were processed for immunohistochemistry using antibodies to aquaporin-1, 2, 3, and 4. RESULTS: Immunoreactivity for aquaporin-1 of sham-operated kidney was detected in the apical and basolateral plasma membrane of proximal tubules and thin limb of Henle loop. That of bilateral ureteral obstructed kidney was decreased in the both tubules, especially in the proximal tubules and thin limb of Henle loop of inner medulla. Immunoreactivity for aquaporin-2 of sham-operated kidney was the most prominent in apical region and moderate in cytoplasm of the principal cells of entire collecting ducts. That of obstructed kidney was markedly decreased in entire collecting duct, especially inner medulla except inner stripe of outer medulla. The decrease was in parallel between the apical region and cytoplasm. Immunoreactivity for aquaporin-3 of sham-operated kidney was the most prominent in the basolateral plasma membrane of principal cells of entire collecting duct. That of obstructed kidney was decreased in entire collecting duct. Papillary epithelium was stained in obstructed kidney. Immunoreactivity for aquaporin-4 of sham-operated kidney was moderate in the basolateral plasma membrane of principal cells of collecting ducts of inner stripe of outer medulla and inner medulla. In obstructed kidney, immunoreactivity was detected in cortical and outer stripe of outer medullary collecting duct, and decreased in inner stripe of outer medulla and inner medulla. A marked heterogeneity was observed in inner medullary collecting duct. CONCLUSION: These results indicate that alterations of expression of aquaporin proteins after bilateral ureteral obstruction may lead to change in renal functions, such as urine concentrating ability.
Abdomen ; Abdominal Cavity ; Animals ; Antibodies ; Aquaporin 2 ; Aquaporins ; Cell Membrane ; Cytoplasm ; Epithelial Cells ; Epithelium ; Extremities ; Humans ; Immunohistochemistry ; Kidney ; Kidney Concentrating Ability ; Ligation ; Loop of Henle ; Male ; Membranes ; Population Characteristics ; Rats ; Rats, Sprague-Dawley ; Silk ; Ureter* ; Ureteral Obstruction* ; Urinary Tract

Prostaglandins (PGs) with best-defined renal functions are PGE2 and prostacyclin (PGI2). These vasodilatory PGs increase renal blood flow and glomerular filtration rate under conditions associated with decreased actual or effective circulating volume, resulting in greater tubular flow and secretion of potassium. Under conditions of decreased renal perfusion, the production of renal PGs serves as an important compensatory mechanism. PGI2 (and possibly PGE2) increases potassium secretion mainly by stimulating secretion of renin and activating the renin-angiotensin system, which leads to increased secretion of aldosterone. In addition, PGE2 is involved in the regulation of sodium and water reabsorption and acts as a counterregulatory factor under conditions of increased sodium reabsorption. PGE2 decreases sodium reabsorption at the thick ascending limb of the loop of Henle probably via inhibition of the Na+-K+-2Cl-cotransporter type 2 (NKCC2). Cyclooxygenase inhibitors may enhance urinary concentrating ability in part through effects to upregulate NKCC2 in the thick ascending limb of Henle's loop and aquaporin-2 in the collecting duct. Thus, they may be useful to treat Bartter's syndrome and nephrogenic diabetes insipidus.
Aldosterone ; Aquaporin 2 ; Bartter Syndrome ; Cyclooxygenase 2 ; Cyclooxygenase 2 Inhibitors ; Cyclooxygenase Inhibitors ; Diabetes Insipidus, Nephrogenic ; Dinoprostone ; Epoprostenol ; Extremities ; Glomerular Filtration Rate ; Kidney ; Kidney Concentrating Ability ; Loop of Henle ; Perfusion ; Potassium ; Prostaglandins ; Renal Circulation ; Renin ; Renin-Angiotensin System ; Sodium ; Water

Type 1 myotonic dystrophy (DM1) is an autosomal-dominant inherited disorder with a multisystem involvement, caused by an abnormal expansion of the CTG sequence of the dystrophic myotonia protein kinase (DMPK) gene. DM1 is a variable multisystem disorder with muscular and nonmuscular abnormalities. Increasingly, endocrine abnormalities, such as gonadal, pancreatic, and adrenal dysfunction are being reported. But, Electrolytes imbalance is a very rare condition in patients with DM1 yet. Herein we present a 42-yr-old Korean male of DM1 with abnormally elevated serum sodium and potassium. The patient had minimum volume of maximally concentrated urine without water loss. It was only cured by normal saline hydration. The cause of hypernatremia was considered by primary hypodipsia. Hyperkalemic conditions such as renal failure, pseudohyperkalemia, cortisol deficiency and hyperkalemic periodic paralysis were excluded. Further endocrine evaluation suggested selective hyperreninemic hypoaldosteronism as a cause of hyperkalemia.
Adult ; Humans ; Hyperkalemia/complications/*diagnosis ; Hypernatremia/complications/*diagnosis ; Hypoaldosteronism/complications/diagnosis ; Kidney Concentrating Ability ; Male ; Myotonic Dystrophy/complications/*diagnosis/*genetics ; Potassium/blood ; Protein-Serine-Threonine Kinases/*genetics ; Sodium/blood

Cystinuria is an inherited disorder characterized by defective renal reabsorption of cystine and dibasic amino acids leading to nephrolithiasis. This study was conducted to analyze the genotypes and phenotypes of pediatric patients with cystinuria. Eight children from Seoul National University Hospital and Asan Medical Center presenting with cystinuria from January 2003 to June 2016 were retrospectively analyzed. Mutational studies were performed by direct sequencing. Two of the 8 were male and 6 were female. The median ages at onset and diagnosis were 1.5 (range, 0.3–13.6) and 2.6 (range, 0.7–16.7) years, respectively. The median followed up was 7.7 (range, 3.4–14.0) years. Mutational analyses were performed in 7 patients and revealed biallelic SLC3A1 mutations (AA genotype) in 4 patients, a single heterozygous SLC3A1 mutation (A- genotype) in 1 patient, biallelic SLC7A9 mutations (BB genotype) in 1 patient, and a single heterozygous SLC7A9 mutation (B- genotype) in 1 patient. Two of the mutations were novel. No genotype-phenotype correlations were observed, except for earlier onset age in patients with non-AA genotypes than in patients with the AA genotype. All patients suffered from recurrent attacks of symptomatic nephrolithiasis, which lead to urologic interventions. At the last follow-up, 3 patients had a mild-to-moderate degree of renal dysfunction. This is the first study of genotypic and phenotypic analyses of patients with cystinuria in Korea.
Age of Onset ; Amino Acids, Diamino ; Child ; Chungcheongnam-do ; Cystine ; Cystinuria* ; Diagnosis ; Female ; Follow-Up Studies ; Genetic Association Studies ; Genotype* ; Humans ; Korea ; Male ; Nephrolithiasis ; Phenotype* ; Renal Reabsorption ; Retrospective Studies ; Seoul