Role of 11â-hydroxysteroid dehydrogenase 2 renal activity in potassium homeostasis in rats with chronic renal failure

Aldosterone concentrations vary in advanced chronic renal failure (CRF). The isozyme 11â-hydroxysteroid dehydrogenase 2 (11â-HSD2), which confers aldosterone specificity for mineralocorticoid receptors in distal tubules and collecting ducts, has been reported to be decreased or normal in patients with renal diseases. Our objective was to determine the role of aldosterone and 11â-HSD2 renal microsome activity, normalized for glomerular filtration rate (GFR), in maintaining K+ homeostasis in 5/6 nephrectomized rats. Male Wistar rats weighing 180-220 g at the beginning of the study were used. Rats with experimental CRF obtained by 5/6 nephrectomy (N = 9) and sham rats (N = 10) were maintained for 4 months. Systolic blood pressure and plasma creatinine (Pcr) concentration were measured at the end of the experiment. Sodium and potassium excretion and GFR were evaluated before and after spironolactone administration (10 mg·kg-1·day-1 for 7 days) and 11â-HSD2 activity on renal microsomes was determined. Systolic blood pressure (means ± SEM; Sham = 105 ± 8 and CRF = 149 ± 10 mmHg) and Pcr (Sham = 0.42 ± 0.03 and CRF = 2.53 ± 0.26 mg/dL) were higher (P < 0.05) while GFR (Sham = 1.46 ± 0.26 and CRF = 0.61 ± 0.06 mL/min) was lower (P < 0.05) in CRF, and plasma aldosterone (Pald) was the same in the two groups. Urinary sodium and potassium excretion was similar in the two groups under basal conditions but, after spironolactone treatment, only potassium excretion was decreased in CRF rats (sham = 0.95 ± 0.090 (before) vs 0.89 ± 0.09 µEq/min (after) and CRF = 1.05 ± 0.05 (before) vs 0.37 ± 0.07 µEq/min (after); P < 0.05). 11â-HSD2 activity on renal microsomes was lower in CRF rats (sham = 0.807 ± 0.09 and CRF = 0.217 ± 0.07 nmol·min-1·mg protein-1; P < 0.05), although when normalized for mL GFR it was similar in both groups. We conclude that K+ homeostasis is ...

Role of 11beta-hydroxysteroid dehydrogenase 2 renal activity in potassium homeostasis in rats with chronic renal failure.

Aldosterone concentrations vary in advanced chronic renal failure (CRF). The isozyme 11beta-hydroxysteroid dehydrogenase 2 (11beta-HSD2), which confers aldosterone specificity for mineralocorticoid receptors in distal tubules and collecting ducts, has been reported to be decreased or normal in patients with renal diseases. Our objective was to determine the role of aldosterone and 11beta-HSD2 renal microsome activity, normalized for glomerular filtration rate (GFR), in maintaining K+ homeostasis in 5/6 nephrectomized rats. Male Wistar rats weighing 180-220 g at the beginning of the study were used. Rats with experimental CRF obtained by 5/6 nephrectomy (N = 9) and sham rats (N = 10) were maintained for 4 months. Systolic blood pressure and plasma creatinine (Pcr) concentration were measured at the end of the experiment. Sodium and potassium excretion and GFR were evaluated before and after spironolactone administration (10 mg.kg-1.day-1 for 7 days) and 11beta-HSD2 activity on renal microsomes was determined. Systolic blood pressure (means +/- SEM; Sham = 105 +/- 8 and CRF = 149 +/- 10 mmHg) and Pcr (Sham = 0.42 +/- 0.03 and CRF = 2.53 +/- 0.26 mg/dL) were higher (P < 0.05) while GFR (Sham = 1.46 +/- 0.26 and CRF = 0.61 +/- 0.06 mL/min) was lower (P < 0.05) in CRF, and plasma aldosterone (Pald) was the same in the two groups. Urinary sodium and potassium excretion was similar in the two groups under basal conditions but, after spironolactone treatment, only potassium excretion was decreased in CRF rats (sham = 0.95 +/- 0.090 (before) vs 0.89 +/- 0.09 microEq/min (after) and CRF = 1.05 +/- 0.05 (before) vs 0.37 +/- 0.07 microEq/min (after); P < 0.05). 11beta-HSD2 activity on renal microsomes was lower in CRF rats (sham = 0.807 +/- 0.09 and CRF = 0.217 +/- 0.07 nmol.min-1.mg protein-1; P < 0.05), although when normalized for mL GFR it was similar in both groups. We conclude that K+ homeostasis is maintained during CRF development despite normal Pald levels. This adaptation may be mediated by renal 11beta-HSD2 activity, which, when normalized for GFR, became similar to that of control rats, suggesting that mineralocorticoid receptors maintain their aldosterone selectivity.

Hepatic 11 beta-hydroxysteroid dehydrogenase 1 involvement in alterations of glucose metabolism produced by acidotic stress in rat

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11 beta-hydroxysteroid dehydrogenase (HSDs) enzymes regulate the activity of glucocorticoids in target organs. HSD1, one of the two existing isoforms, locates mainly in CNS, liver and adipose tissue. HSD1 is involved in the pathogenesis of diseases such as obesity, insulin resistance, arterial hypertension and the Metabolic Syndrome. The stress produced by HCl overload triggers metabolic acidosis and increases liver HSD1 activity associated with increased phosphoenolpyruvate carboxykinase, a regulatory enzyme of gluconeogenesis that is activated by glucocorticoids, with increased glycaemia and glycogen breakdown. The aim of this study was to analyze whether the metabolic modifications triggered by HCl stress are due to increased liver HSD1 activity. Glycyrrhetinic acid, a potent HDS inhibitor, was administered subcutaneously (20 mg/ml) to stressed and unstressed four months old maleSprague Dawley rats to investigate changes in liver HSD1, phosphoenolpyruvate carboxykinase (PECPK) and glycogen phosphorylase activities and plasma glucose levels. It was observed that all these parameters increased in stressed animals, but that treatment with glycyrrhetinic acid significantly reduced their levels. In conclusion, our results demonstrate the involvement of HSD1 in stress induced carbohydrate disturbances and could contribute to the impact of HSD1 inhibitors on carbohydrate metabolism and its relevance in the study of Metabolic Syndrome Disorder and non insulin-dependent diabetes mellitus (AU)

Hepatic 11 beta-hydroxysteroid dehydrogenase 1 involvement in alterations of glucose metabolism produced by acidotic stress in rat.

11 beta-hydroxysteroid dehydrogenase (HSDs) enzymes regulate the activity of glucocorticoids in target organs. HSD1, one of the two existing isoforms, locates mainly in CNS, liver and adipose tissue. HSD1 is involved in the pathogenesis of diseases such as obesity, insulin resistance, arterial hypertension and the Metabolic Syndrome. The stress produced by HCl overload triggers metabolic acidosis and increases liver HSD1 activity associated with increased phosphoenolpyruvate carboxykinase, a regulatory enzyme of gluconeogenesis that is activated by glucocorticoids, with increased glycaemia and glycogen breakdown. The aim of this study was to analyze whether the metabolic modifications triggered by HCl stress are due to increased liver HSD1 activity. Glycyrrhetinic acid, a potent HDS inhibitor, was administered subcutaneously (20 mg/ml) to stressed and unstressed four months old maleSprague Dawley rats to investigate changes in liver HSD1, phosphoenolpyruvate carboxykinase (PECPK) and glycogen phosphorylase activities and plasma glucose levels. It was observed that all these parameters increased in stressed animals, but that treatment with glycyrrhetinic acid significantly reduced their levels. In conclusion, our results demonstrate the involvement of HSD1 in stress induced carbohydrate disturbances and could contribute to the impact of HSD1 inhibitors on carbohydrate metabolism and its relevance in the study of Metabolic Syndrome Disorder and non insulin-dependent diabetes mellitus.

Evaluación de medios de cultivo selectivos para el aislamiento de Salmonella en producción avícola / Evaluation of selective culture media for isolation of Salmonella from poultry

Se evaluó el desempeño de los medios agar Rambach, agar xilosa-lisina-desoxicolato (XLD) con el agregado de diferentes concentraciones de tergitol tipo 4 o sulfato de sodio y de 7-etil-2-metil-4-undecanol (XLDT4), agar Salmonella-Shigella (SS) y agar sulfito de bismuto según Wilson-Blair (SB) utilizando serovariedades de Salmonella spp. y otras especies bacterianas de la flora intestinal de las aves. Los medios de cultivo selectivos fueron evaluados mediante recuento de bacterias viables, comparando estos resultados con los del agar base Columbia (ABC) adicionado con sangre bovina al 7 por ciento, para lo cual se emplearon las serovariedades de Salmonella spp. que con mayor frecuencia se aíslan en las aves de nuestro país. Además se analizaron muestras provenientes de pollos experimentalmente inoculados con distintas serovariedades de Salmonella. Los medios Rambach, SS y XLD o XLDT4 son adecuados para el aislamiento de salmonelas. En cambio el agar SB fue muy inhibidor para las salmonelas de interés veterinario. El agregado de novobiocina o tergitol al medio XLD no inhibio completamente a todas las cepas de Proteus. En el agar Rambach comercial no creció ninguna de las cepas de Proteus que habían desarrollado en los otros medios. Diversas bacterias contaminantes produjeron colonias similares a Salmonella en los agares Rambach, SS, XLD y XLDT4. Dado que las especies bacterianas contaminantes que desarrollan en los medios de cultivo son diferentes, es recomendable optimizar el diagnóstico sembrando las muestras en los agares SS, XLD o XLDT4 y simultáneamente también en agar Rambach

Evaluación de medios de cultivo selectivos para el aislamiento de Salmonella en producción avícola / Evaluation of selective culture media for isolation of Salmonella from poultry

Se evaluó el desempeño de los medios agar Rambach, agar xilosa-lisina-desoxicolato (XLD) con el agregado de diferentes concentraciones de tergitol tipo 4 o sulfato de sodio y de 7-etil-2-metil-4-undecanol (XLDT4), agar Salmonella-Shigella (SS) y agar sulfito de bismuto según Wilson-Blair (SB) utilizando serovariedades de Salmonella spp. y otras especies bacterianas de la flora intestinal de las aves. Los medios de cultivo selectivos fueron evaluados mediante recuento de bacterias viables, comparando estos resultados con los del agar base Columbia (ABC) adicionado con sangre bovina al 7 por ciento, para lo cual se emplearon las serovariedades de Salmonella spp. que con mayor frecuencia se aíslan en las aves de nuestro país. Además se analizaron muestras provenientes de pollos experimentalmente inoculados con distintas serovariedades de Salmonella. Los medios Rambach, SS y XLD o XLDT4 son adecuados para el aislamiento de salmonelas. En cambio el agar SB fue muy inhibidor para las salmonelas de interés veterinario. El agregado de novobiocina o tergitol al medio XLD no inhibio completamente a todas las cepas de Proteus. En el agar Rambach comercial no creció ninguna de las cepas de Proteus que habían desarrollado en los otros medios. Diversas bacterias contaminantes produjeron colonias similares a Salmonella en los agares Rambach, SS, XLD y XLDT4. Dado que las especies bacterianas contaminantes que desarrollan en los medios de cultivo son diferentes, es recomendable optimizar el diagnóstico sembrando las muestras en los agares SS, XLD o XLDT4 y simultáneamente también en agar Rambach (AU)

[Evaluation of selective culture media for the isolation of Salmonella from poultry]. / Evaluación de medios de cultivo selectivos para el aislamiento de Salmonella en producción avícola.

Rambach agar, xylose-lysine-deoxycholate agar (XLD) with different concentrations of Tergitol 4 or 7 ethyl-2 methyl-4 undecanol hydrogen sulphate, sodium salt (XLDT4), Salmonella-Shigella agar (SS) and bismuth sulfite agar according to Wilson-Blair (BS) were evaluated using Salmonella spp. serovars and other bacterial species from the intestinal flora of poultry. Growth of the most common Salmonella serovars isolated from chickens in our country were evaluated using a viable counting technique on the different selective media and these results were compared with those obtained on Columbia base (ABC) agar plus 7% bovine blood (Table 1). Samples from Salmonella experimentally inoculated chickens were also examined. Results showed that Rambach, SS and XLD or XLDT4 were all satisfactory for isolation of Salmonella. Bismuth Sulfite agar was too inhibitory for bacteria important in veterinary practice. The characteristic colonies of Salmonella and other common fecal contaminant bacteria growing on SS, Rambach, XLDT4 and SB are shown in Table 2. Addition of tergitol or novobiocin to XLD agar did not completely inhibit the growth of all Proteus spp. strains examined. None of the Proteus spp. strains able to multiply on SS, XLD or XLDT4 agar grew on the commercial Rambach agar. Several different contaminant bacterial species produced Salmonella-like colonies on Rambach, SS, XLD and XLDT4 agars. Because these contaminant bacterial species are different it is advisable to improve the diagnosis by culturing samples on SS, XLD or XLDT4 agar and also simultaneously on Rambach agar.

Evaluación de medios de cultivo selectivos para el aislamiento de Salmonella en producción avícola. / [Evaluation of selective culture media for the isolation of Salmonella from poultry]

Rambach agar, xylose-lysine-deoxycholate agar (XLD) with different concentrations of Tergitol 4 or 7 ethyl-2 methyl-4 undecanol hydrogen sulphate, sodium salt (XLDT4), Salmonella-Shigella agar (SS) and bismuth sulfite agar according to Wilson-Blair (BS) were evaluated using Salmonella spp. serovars and other bacterial species from the intestinal flora of poultry. Growth of the most common Salmonella serovars isolated from chickens in our country were evaluated using a viable counting technique on the different selective media and these results were compared with those obtained on Columbia base (ABC) agar plus 7

bovine blood (Table 1). Samples from Salmonella experimentally inoculated chickens were also examined. Results showed that Rambach, SS and XLD or XLDT4 were all satisfactory for isolation of Salmonella. Bismuth Sulfite agar was too inhibitory for bacteria important in veterinary practice. The characteristic colonies of Salmonella and other common fecal contaminant bacteria growing on SS, Rambach, XLDT4 and SB are shown in Table 2. Addition of tergitol or novobiocin to XLD agar did not completely inhibit the growth of all Proteus spp. strains examined. None of the Proteus spp. strains able to multiply on SS, XLD or XLDT4 agar grew on the commercial Rambach agar. Several different contaminant bacterial species produced Salmonella-like colonies on Rambach, SS, XLD and XLDT4 agars. Because these contaminant bacterial species are different it is advisable to improve the diagnosis by culturing samples on SS, XLD or XLDT4 agar and also simultaneously on Rambach agar.