BACKGROUNDWe require a stable model to understand the molecular mechanism by which isolated hyperphosphatemia induces hyperparathyroidism secondary to chronic renal failure. The present study established a rat model of hyperphosphatemia-induced secondary hyperparathyroidism in chronic renal failure.

METHODSTwenty-nine rats with 5/6 nephrectomy (Nx) were divided into three groups and were fed for 10 weeks on a high phosphate diet (1.2% phosphate) starting from three different post-Nx time points. Parathyroid hormone mRNA in parathyroid gland was measured by real-time PCR and parathyroid cell hyperplasia was tested by proliferating cell nuclear antigen (PCNA) assay.

RESULTSThe 10 rats fed a high phosphate diet starting from the fourth week post-Nx had isolated hyperphosphatemia and excess synthesis/secretion of parathyroid hormone, and hyperplasia of the parathyroid glands were induced (r = 0.86 - 0.97, P < 0.001), but the levels of serum calcium and 1, 25 (OH)2D3 did not change.

CONCLUSIONA rat model of hyperphosphatemia-induced secondary hyperparathyroidism in chronic renal failure was established by 5/6 Nx and 10 weeks-high phosphate diet starting from the fourth week post-Nx.

Animals ; Disease Models, Animal ; Hyperparathyroidism ; etiology ; Hyperphosphatemia ; complications ; Kidney Failure, Chronic ; complications ; Male ; Nephrectomy ; methods ; Rats ; Rats, Wistar

BACKGROUNDHyperphosphatemia in renal failure has been identified as a major role in the pathogenesis of hyperparathyroidism that is independent of changes in serum calcium and 1,25(OH)(2)D(3). The aim of this study was to evaluate the expression of parathyroid Pit-1 in hyperphosphatemia-induced secondary hyperparathyroidism (SHPT) of chronic renal failure (CRF) rats.

METHODSWistar rats with CRF induced by 5/6 nephrectomy were ramdomly fed with diet containing 1.2% inorganic phosphate (Pi, high phosphate (HP) group, n = 9) or 0.2% Pi (low phosphate (LP) group, n = 9) for 10 weeks starting from the fourth week after the surgery. Another 7 nephrectomy rats with HP diet were intraperitoneally injected with phosphonoformic acid (PFA, the specific inhibitor of Pit-1, HP + PFA group) 0.15 g/kg every other day for 10 weeks starting from HP diet. Another 6 HP rats injected with the same amount of normal saline as the control of the HP + PFA group (HP + saline group). At the same time, 9 rats with sham surgery received HP diet as the controls. At the 4th week and 14th week, blood was taken for measurement of serum creatinine (SCr), serum calcium (SCa), serum phosphorus (SPi), 1,25(OH)(2)D(3) and intact parathyroid hormone (iPTH). At the 14th week, two parathroid glands (PTGs) of each rat were removed by microsurgery, one gland for immunohistochemistry analysis of proliferating cell nuclear antigen (PCNA), the other one for detection of Pit-1 by Western blotting, and for the measurement of Pit-1 mRNA and PTH mRNA by real-time quantitative polymerase chain reaction.

RESULTSIn nephrectomy rats, high dierary phosphate induced a marked increase in serum phosphate, iPTH, PTH mRNA and PCNA parathyroid cells, accompanying Pit-1 and its mRNA in parathyroid gland increased significantly. However, serum Ca and 1,25(OH)(2)D(3) remained unchanged. PFA decreased Pit-1 and its mRNA levels to reduce intact PTH, PTH mRNA and PCNA-positive parathyroid cells.

CONCLUSIONSExpression of parathyroid Pit-1 in hyperphosphatemia-induced SHPT of CRF rats was upregulated. Pit-1 may mediate the stimulation to parathyroid gland by hyperphosphatemia.

Animals ; Blotting, Western ; Hyperparathyroidism, Secondary ; etiology ; metabolism ; Hyperphosphatemia ; complications ; Immunohistochemistry ; Kidney Failure, Chronic ; complications ; Male ; Polymerase Chain Reaction ; Rats ; Rats, Wistar ; Sodium-Phosphate Cotransporter Proteins, Type III ; genetics ; metabolism

BACKGROUND/AIMS: The aim of this study was to compare polyethylene glycol (PEG) 4 L, split method of PEG 4 L and PEG 2 L plus sodium phosphate (NaP) in the aspect of bowel preparation quality, safety, patients' compliance and preference. METHODS: Total 249 subjects were prospectively enrolled and received bowel preparation for colonoscopy from August to October in 2010; PEG 4 L (93 subjects), split method of 4 L PEG (74 subjects) and PEG 2 L plus NaP 90 mL group (82 subjects). To investigate the completion, preference for bowel preparation and safety, a questionnaire survey was conducted before colonoscopy. RESULTS: There were no significant intergroup differences in the aspect of completion of preparation, cecal intubation time and success rate. Satisfaction and preference were higher in PEG 2 L plus NaP 90 mL and split method of 4 L PEG compared with PEG 4 L. In the aspect of the bowel preparation quality PEG 4 L showed significantly higher quality in the morning colonoscopy (p<0.001). However, in the afternoon colonoscopy PEG 2 L plus NaP 90 mL showed better result than PEG 4 L (p=0.009). Hyperphosphatemia was most frequently observed in PEG 2 L plus NaP 90 mL, but no severe adverse events occurred (p<0.001). CONCLUSIONS: PEG 4 L showed better result than split method of 4 L PEG or PEG 2 L plus NaP 90 mL in the aspect of bowel preparation quality and safety.
Adult ; Aged ; Cathartics/adverse effects/*pharmacology ; Colon/anatomy & histology/*drug effects ; Colonoscopy ; Female ; Humans ; Hyperphosphatemia/etiology ; Male ; Middle Aged ; Patient Compliance ; Phosphates/adverse effects/*pharmacology ; Polyethylene Glycols/adverse effects/*pharmacology ; Prospective Studies ; Questionnaires ; Time Factors