Resection of the renal papillae in rats

Characterization of a mouse model of chronic uremia

A mouse model of renal failure, which is induced by the sequential electrocoagulation of the right renal cortex and left nephrectomy, was examined for the capacity to reproduce the characteristics of chronic uremia. Assessment was conducted six weeks after the second surgical procedure in 13 week old female C57BL/6 inbred mice with renal failure and in normal and sham-operated controls. The surgery, which was well tolerated, was free of local and systemic signs of inflammation or infection. Growth was significantly delayed in all animals post surgery however renal failure mice presented the most severe growth retardation. Biochemical analysis of plasma revealed multiple abnormalities with commensurate elevations of urea and creatinine. In addition to the expected hyperphosphatemia, hyperkalemia and acidosis, a significant increase in cholesterol was present. Furthermore, in contrast to controls, renal failure mice produced large volumes of urine which contained significant levels of protein. Renal failure mice presented profound hematological changes in the red cell series in which anemia was evident. Changes in plasma biochemistry and in bone histology revealed the presence of severe secondary hyperparathyroidism. It was therefore concluded that the described mouse model of chronic renal failure presented characteristics consistent with those observed clinically in end-stage renal disease.

Chemical renal medullectomy. Effect on urinary prostaglandin E2 and plasma renin in response to variations in sodium intake and in relation to blood pressure

We have studied the possible vasodepressor role of the renal medulla by chemical medullectomy. Bromoethylamine hydrobromide (200 mg/kg) was injected to induce selective renal medullary necrosis in rats. The acute effects on sodium balance and long-term effects on blood pressure, plasma renin concentration (PRC) and urinary prostaglandin E2 (PGE2) were studied and compared with saline injected controls. There was an immediate and sustained increase in urine volume of low osmolality. Direct blood pressure in conscious free-moving animals was higher at 2 and 10 weeks after injection in medullary-damaged rats, although this was only significant at 10 weeks (136 +/- 3.3 vs 118 +/- 4.5 mm Hg, p less than 0.01). An initial negative sodium balance returned to normal by 7 days and rats with established medullary damage tolerated a wide range of sodium intakes. Although there was no evidence of sodium retention on the normal diet, with very high sodium loads some sodium retention was apparent since PRC was suppressed and body weight increased. Plasma creatinine and creatinine clearance were normal. PRC in rats with medullary damage was unchanged on normal diet and rose to similar levels as in control rats on low sodium intake. Urinary PGE2 was markedly reduced (148 +/- 54 vs 536 +/- 71 ng/day, p less than 0.01) in medullary damaged rats, consistent with the renal medulla being the major source of urinary PGE2. High salt intake increased urinary PGE2 in normal and proportionally in medullary damaged rats, whereas on a low sodium intake, urinary PGE2 was not different from that on the normal diet in either group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal model of aluminum-induced osteomalacia: role of chronic renal failure

Both aluminum toxicity and a relative deficiency of parathyroid hormone have been implicated in the development of osteomalacia in dialysis patients. To study the effect of intraperitoneal (IP) aluminum injections on bone histology and parathyroid hormone and to determine if chronic renal failure accentuates aluminum toxicity, rats were divided into five groups: normals (N); low dose aluminum (LDA), 0.1 mg IP aluminum daily; high dose aluminum (HDA), 1.0 mg IP aluminum daily; chronic renal failure (CRF); and chronic renal failure plus high dose aluminum (CRF-HDA). At the conclusion of the study, there were no differences between N and LDA rats. Between the other groups, marked differences were observed. Compared to N rats, the relative osteoid volume (P less than 0.02) and the osteoid seam width (P less than 0.001) were increased in HDA, CRF, and CRF-HDA rats. Percent resorption and osteoclasts/mm2 were increased in CRF rats (P less than 0.02) and decreased in HDA rats (P less than 0.05). Compared to N rats, the amino terminal parathyroid hormone was decreased in HDA rats (P less than 0.02) despite the presence of hypocalcemia. These data suggest that (1) aluminum toxicity produces osteomalacia; (2) a relative parathyroid hormone deficiency may be a contributory factor; (3) chronic renal failure increases the severity of aluminum-induced osteomalacia; and (4) chronic renal failure alone does not result in osteomalacia.

The effect of unilateral papillectomy on the juxtaglomerular granulated cells

The changes of the juxtaglomerular index values in the superficial, deep and whole cortical areas of rat kidneys after unilateral papillectomy were analyzed. On the papillectomized side the JGI values showed an increase in the deep, and a decrease in the superficial cortical zone. The changes proved to be significant during the whole experimental period in the juxtamedullary index and between the 4--14 postoperative days in the superficial index values. The tendency of the changes of JGI in the contralateral kidneys was similar to those of the papillectomized kidneys, but significant differences were registered less constantly. These changes are probably the consequences of haemodynamic factors. Papillectomy is considered an incompetent model for studying the regulatory function of macula densa in the synthesis of renin.