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The effects of prednisolone on the rat enterocyte at a subcellular level.

1. Enterocytes, isolated from the proximal jejunum and distal ileum of normal and prednisolone-treated rats, were homogenized and fractionated by isopycnic centrifugation on sucrose density gradients. The distributions of marker enzymes for the principal subcellular organelles, RNA and protein were determined and related to the activities per enterocyte. 2. In enterocytes fromthe jejunum and ileum of prednisolone-treated animals the activities of particulate brush-border enzymes and of both soluble and mitochondrial malate dehydrogenase were increased compared with those of the control system. The equilibrium density of the brush borders was enhanced in the prednisolone-treated jejunum. The modal densities of the other organelles were unaltered by prednisolone administration. 3. There was a large increase in the total RNA content of enterocytes from the jejunum and ileum of prednisolone-treated animals. This was predominantly associated with a distinct particulate component, indicative of a proliferation of the rough endoplasmic reticulum and consistent with an enhanced rate of protein synthesis. 4. Studies of latent brush-border enzyme activities, the mechanical fragility of isolated brush borders and electron microscopy suggest that steroid administration results in no marked alterations in the gross conformation of the brush-border membrane or in the orientation of the enzymes within the membrane.

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Protective effect of prostaglandin [PGE2] and in glycerol-induced acute renal failure in rats.

1. Acute renal failure was induced in female Sprague-Dawley rats by the subcutaneous injection of glycerol. 2. Four groups of rats were studied; all animals received a glycerol challenge. Group A (control) were sham-operated only, group B received an infusion of sodium chloride solution (150 mmol/l; saline) for 24 h, group C received an infusion containing prostaglandin E2 (PGE2, 1.7 micronmol/l) in saline and group D a solution containing PGE2 (3.4 micronmol/l) in saline. 3. All rats were killed 48 h after glycerol challenge. The degree of renal impairment was assessed by serum creatinine concentration, which did not differ in sham-operated animals and the group receiving saline alone. The group of rats receiving the lower dose dose of PGE2 has a significantly lower mean serum creatinine concentration than the saline-infused control rats (P less than 0.0025). Creatinine concentration was further lowered by the higher dose of PGE2 but there was not a significant difference in the number of rats showing severe tubular necrosis histologically. 4. The study demonstrates that intravenous infusion of prostaglandin E2 has a protective influence on glycerol-induced renal failure in the rat; the protection afforded may be due to the vasodilator effect of PGE2 and/or an effect on glomerular permeability.

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