The present study was designed to investigate the effect of administration of adrenomedullin (ADM) into subfornical organ (SFO) on renal tubular Na(+),K(+)-ATPase activity in rats. Rats under anesthesia were injected with ADM 0.1 mL (20 ng/mL) via an implanted cannula into SFO (n=6). Plasma ADM and serum endogenous digitalis-like factor (EDLF) levels were assayed with radioimmunoassay, and urine samples were collected via a canoula intubated in bladder. Urinary sodium concentration was assayed with flame spectrophotometry. Single proximal renal tubule segments were obtained by hand under stereomicroscope and its Na(+),K(+)-ATPase activity was measured by liquid scintillation counting. In addition, single proximal renal tubule segments from normal rats (n=6) were incubated with serum from animals administered with ADM into SFO, and then the Na(+),K(+)-ATPase activity was determined. The results showed that both urinary volume and sodium excretion amounted to the peak value at 30 min after ADM administration, and sustained a significant high level at 60 min (P<0.01). At 30 min after ADM administration, there was a significant increase in serum EDLF and a decrease in Na(+),K(+)-ATPase activity of proximal tubule (P<0.01, respectively), but not in plasma ADM level. Na(+),K(+)-ATPase activity was decreased significantly in single proximal renal tubule segments from normal rats incubated with serum from rats administered with ADM into SFO (P<0.01). These results suggest that the diuretic and natriuretic responses following administration of ADM into SFO are associated with the inhibition of renal tubule Na(+),K(+)-ATPase activity. The inhibition of renal tubule Na(+),K(+)-ATPase activity is related to the increase in the serum level of EDLF.
Adrenomedullin ; pharmacology ; Animals ; Kidney Tubules, Proximal ; drug effects ; enzymology ; Rats ; Sodium-Potassium-Exchanging ATPase ; metabolism ; Subfornical Organ

AIMTo investigate the effect of micro-injection Ang II into the subfornical organ (SFO) on the proximal tubules (PT) Na+, K(+)-ATPase activity in rats and its mechanism.

METHODSSFO in SD rats was administrated respectively with Ang II (20 ng), or losartan (5 microg) and AngII (20 ng) successively. The levels of serum EDLS and plasm AngII were assessed with radioimmunoassay (RIA). The PT segments were microdissected freehand and their Na+, K(+)-ATPase activities were assessed by liquid scintillation counter (LSC).

RESULTSThe serum EDLS levels increased significantly compared with a CSF group after SFO administration with Ang II; The Na+, K(+)-ATPase activities in PT segments decreased significantly at 30 min and 60 min after SFO administration with Ang II. There was a negative linear correlation between serum EDLS level and the Na+, K(+)-ATPase activity of PT segments in rats administrated with Ang II (r = -0.938).

CONCLUSIONInhibition of the Na+, K(+)-ATPase activity in PT as a result of administration of Ang II in SFO is mediated by AT1 receptors. The increase in EDLS release may play an important role in this inhibition.

Angiotensin II ; administration & dosage ; pharmacology ; Animals ; Kidney Tubules, Proximal ; drug effects ; enzymology ; Male ; Rats ; Rats, Sprague-Dawley ; Sodium-Potassium-Exchanging ATPase ; metabolism ; Subfornical Organ

OBJECTIVETo investigate the effect of cytochrome P450 isozymes on aristolochic acid induced cytotoxicity on renal proximal tubular epithelial cell (cell line HK-2).

METHODHuman renal tubular cells (cell line HK-2), were treated with aristolochic acid (AA) alone or in combination with cytochrome P450 isozymes inhibitors, including alpha-naphthoflavone (CYP450 1A1 and 1 A2 inhibitors), ketoconazole (CYP450 3A4 inhibitor), sodium diethyldithiocarbamate (CYP450 2A6 and 2E1 inhibitors), quinidine (CYP450 2D inhibitor), alpha-lipoic acid (NADPH: P450 reductase inhibitor), sulfaphenazole (CYP450 2C inhibitor) in the presence or absence of liver microsome(S9). The inhibition of cell proliferation rate was studied by MTT assay and the lactate dehydrogenase release rate was determined with continuous monitoring method.

RESULTAA inhibits cell proliferation and promotes the release of LDH over the range of 12.5-100 mg x L(-1), in a dose-dependent manner. Addition of S9 into the culture system reduced AA cytotoxicity, with the cell proliferation inhibition reducing and the release of LDH decreasing (AA + S9 group vs the same concentration of AA alone group, P < 0.05). In the absence of S9, ketoconazole or alpha-naphthoflavone has no obvious effect on AA cytotoxicity, however,under the conditions of adding S9, ketoconazole or alpha-naphthoflavone enhances AA cytotoxicity. Other inhibitors of CYP450 isozymes has no distinct effect on AA cytotoxicity.

CONCLUSIONThe microsomal enzyme of Liver can reduce the AA cytotoxicity, and CYP450 3A, CYP450 1A may be the major cytochrome P450 isozymes which impact AA cytotoxicity.

Animals ; Aristolochic Acids ; toxicity ; Cell Line ; Cell Proliferation ; drug effects ; Cytochrome P-450 Enzyme Inhibitors ; Cytochrome P-450 Enzyme System ; metabolism ; Cytotoxicity, Immunologic ; drug effects ; Enzyme Inhibitors ; pharmacology ; Humans ; Kidney Tubules ; drug effects ; enzymology ; immunology ; Male ; Rats ; Rats, Wistar

OBJECTIVE: To determine the effect of integrin-linked kinase(ILK) in renal tubular epithelial cells and its relation to tubular epithelial-myofibroblast transdifferentiation. METHODS: Wistar rats were randomly divided into 3 groups, Group normal control (n=10), Group diabetic without therapy(n=10) and Group diabetic with Losartan 20mg/(kg . d)(n=10). Five rats were killed in each group at the 8th and 16th week. The left kidneys were kept for HE and Masson staining to observe the pathological variations in the renal interstitium. ILK, alpha-SMA and Vimentin in renal tubular epithelial cells were detected by immunohistochemistry analysis. RESULTS: Compared with the control group, ILK, alpha-SMA and Vimentin in renal tubular epithelial cells in Group diabetes gradually increased in immunohistochemistry (P<0.01); ILK was consistent with the pathological variation of renal interstitium and was positively correlated to alpha-SMA(rs=0.621, P<0.05). In comparison with the Group diabetes, the expression of ILK, alpha-SMA and Vimentin in renal tubular epithelial cells was apparently declined (P<0.01) in Group diabetes with Losartan. CONCLUSION Tubular epithelial myofibroblast transdifferentiation and the over-expression of ILK, between which there may be significant connections, are important events in the progression of diabetic nephropathy. Losartan, a blocker of angiotension II type I receptor, which may down-regulate the expression of ILK in diabetic renal tubular epithelial cells, can restrain the procession of epithelial-myofibroblast transdifferentiation.
Actins ; biosynthesis ; Animals ; Cell Transdifferentiation ; Diabetes Mellitus, Experimental ; drug therapy ; physiopathology ; Diabetic Nephropathies ; drug therapy ; physiopathology ; Epithelial Cells ; drug effects ; enzymology ; pathology ; Fibroblasts ; drug effects ; enzymology ; pathology ; Immunohistochemistry ; Kidney Tubules ; pathology ; Losartan ; pharmacology ; therapeutic use ; Male ; Protein-Serine-Threonine Kinases ; biosynthesis ; Random Allocation ; Rats ; Rats, Wistar ; Vimentin ; biosynthesis

OBJECTIVETo observe the effect of Compound Shenhua Tablet (, SHT) on the sodium-potassium- exchanging adenosinetriphosphatase (Na(+)-K(+)-ATPase) in the renal tubular epithelial cells of rats with acute ischemic reperfusion and to investigate the mechanisms underlying the effects of SHT on renal ischemic reperfusion injury (RIRI).

METHODSFifty male Wistar rats were randomly divided into the sham surgery group, model group, astragaloside group [150 mg/(kg·d)], SHT low-dose group [1.5 g/(kg·d)] and SHT high-dose group [3.0 g/(kg·d)], with 10 rats in each group. After 1 week of continuous intragastric drug administration, surgery was performed to establish the model. At either 24 or 72 h after the surgery, 5 rats in each group were sacrificed, blood biochemistry, renal pathology, immunoblot and immunohistochemical examinations were performed, and double immunofluorescence staining was observed under a laser confocal microscope.

RESULTSCompared with the sham surgery group, the serum creatinine (SCr) and blood urea nitrogen (BUN) levels were significantly increased, Na(+)-K(+)-ATPase protein level was decreased, and kidney injury molecule-1 (KIM-1) protein level was increased in the model group after the surgery (P<0.01 or P<0.05). Compared with the model group, the SCr, BUN, pathological scores, Na(+)-K(+)-ATPase, and the KIM-1 protein level of the three treatment groups were significantly improved at 72 h after the surgery (P<0.05 or P<0.01). And the SCr, BUN of the SHT low- and high-dose groups, and the pathological scores of the SHT high-dose group were significantly lower than those of the astragaloside group (P<0.05). The localizations of Na(+)-K(+)-ATPase and megalin of the model group were disrupted, with the distribution areas overlapping with each other and alternately arranged. The severity of the disruption was slightly milder in three treatment groups compared with that of the model group. The results of immunofluorescence staining showed that the SHT high-dose group had a superior effect as compared with the astragaloside group and the SHT low-dose group.

CONCLUSIONSThe SHT effectively alleviated RIRI caused by ischemic reperfusion, promoted the recovery of the polarity of renal tubular epithelial cells, and protected the renal tubules. The therapeutic effects of SHT were superior to those of astragaloside as a single agent.

Acute Disease ; Animals ; Blood Urea Nitrogen ; Cell Adhesion Molecules ; metabolism ; Chromatography, Liquid ; Creatinine ; blood ; Drugs, Chinese Herbal ; pharmacology ; therapeutic use ; Fluorescent Antibody Technique ; Immunoblotting ; Kidney Function Tests ; Kidney Tubules ; blood supply ; drug effects ; enzymology ; pathology ; Low Density Lipoprotein Receptor-Related Protein-2 ; metabolism ; Male ; Rats ; Rats, Wistar ; Reperfusion Injury ; drug therapy ; enzymology ; pathology ; Saponins ; analysis ; Sodium-Potassium-Exchanging ATPase ; metabolism ; Staining and Labeling ; Tablets

BACKGROUND/AIMS: Renal hypoxia is involved in the pathogenesis of diabetic nephropathy. Pentoxifyllin (PTX), a nonselective phosphodiesterase inhibitor, is used to attenuate peripheral vascular diseases. To determine whether PTX can improve renal hypoxia, we investigated its effect in the streptozocin (STZ)-induced diabetic kidney. METHODS: PTX (40 mg/kg, PO) was administered to STZ-induced diabetic rats for 8 weeks. To determine tissue hypoxia, we examined hypoxic inducible factor-1alpha (HIF-1alpha), heme oxygenase-1 (HO-1), vascular endothelial growth factor (VEGF), and glucose transporter-1 (GLUT-1) levels. We also tested the effect of PTX on HIF-1alpha in renal tubule cells. RESULTS: PTX reduced the increased protein creatinine ratio in diabetic rats at 8 weeks. HIF-1alpha, VEGF, and GLUT-1 mRNA expression increased significantly, and the expression of HO-1 also tended to increase in diabetic rats. PTX significantly decreased mRNA expression of HIF-1alpha and VEGF at 4 and 8 weeks, and decreased HO-1 and GLUT-1 at 4 weeks. The expression of HIF-1alpha protein was significantly increased at 4 and 8 weeks in tubules in the diabetic rat kidney. PTX tended to decrease HIF-1alpha protein expression at 8 weeks. To examine whether PTX had a direct effect on renal tubules, normal rat kidney cells were stimulated with CoCl2 (100 microM), which enhanced HIF-1alpha mRNA and protein levels under low glucose conditions (5.5 mM). Their expressions were similar even after high glucose (30 mM) treatment. PTX had no effect on HIF-1alpha expression. CONCLUSIONS: PTX attenuates tubular hypoxia in the diabetic kidney.
Animals ; Anoxia/*drug therapy/enzymology/etiology/genetics ; Cell Line ; Cobalt/pharmacology ; Diabetes Mellitus, Experimental/*complications ; Diabetic Nephropathies/*drug therapy/enzymology/etiology/genetics ; Disease Models, Animal ; Gene Expression Regulation/drug effects ; Glucose/metabolism ; Glucose Transporter Type 1/genetics ; Heme Oxygenase (Decyclizing)/genetics/metabolism ; Hypoxia-Inducible Factor 1, alpha Subunit/genetics/metabolism ; Kidney Tubules/*drug effects/enzymology ; Male ; Pentoxifylline/*pharmacology ; Phosphodiesterase Inhibitors/*pharmacology ; RNA, Messenger/metabolism ; Rats ; Rats, Sprague-Dawley ; Streptozocin ; Time Factors ; Vascular Endothelial Growth Factor A/genetics