Consumo de benzodiacepinas en una comuna de la región metropolitana de Rosario, provincia de Santa Fe, Argentina / Benzodiazepines use in a commune in the Rosario Metropolitan Area, Santa Fe Province, Argentina

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Ischaemia/reperfusion in rat renal cortex: vesicle leakiness and Na+, K+-ATPase activity in membrane preparations.

BACKGROUND: Despite the central role of Na(+), K(+)-ATPase (NKA) in ischaemic renal injury (IRI), cortical NKA activity values during renal ischaemia remain controversial. In this study, we explore why cortical NKA activity shows such behaviour during ischaemia in rats. METHODS: Ischaemia was induced by unilateral renal artery clamping (40 min, I) followed or not by reperfusion (60 min, IR). NKA alpha- and beta-subunit abundance was analysed by western blot. We studied the NKA detergent sodium dodecyl sulphate (SDS) enzymatic activation in isolated membrane preparations from control and ischaemic kidneys. RESULTS: NKA activity was diminished in I cortical homogenates (C = 9.3 +/- 1.1, I = 4.7 +/- 1.1* micromol Pi/h mg Prot, n = 4-6, *P < 0.05 versus C). This was rapidly recovered after reperfusion (IR = 9.9 +/- 1.2 micromol Pi/h mg Prot). alpha-subunit levels were increased, while beta-subunit was unchanged. At SDS 0.9 mg/ml (maximal detergent activation), the activities were indistinguishable (C = 90.5 +/- 2.2, I = 91.4 +/- 15.1 micromol Pi/h mg Prot). The analysis of detergent activation of NKA activity is widely used to estimate membrane leakiness in plasma membrane preparations. Our results suggest a higher population of sealed impermeable vesicles in preparations from ischaemic renal tissue. CONCLUSION: The well-known effect of ischaemia on renal cell cytoskeleton could explain the observed changes in the leakiness of membrane vesicles.

Urinary concentrating mechanism and Aquaporin-2 abundance in rats chronically treated with aluminum lactate.

The aim of this work was to study the effects of chronic administration of aluminum (Al) on the urinary concentrating and diluting mechanisms in the distal tubules and collecting ducts. Male Wistar rats were chronically treated with aluminum lactate for 12 weeks (0.575 mg Al/100g of body weight, i.p., three times per week). After 12 weeks, renal function of control and Al-treated rats was evaluated by clearance techniques. To study urinary concentrating mechanisms, renal function was also measured in control and Al-treated rats deprived of water, after the administration of desmopressin (vasopressin agonist) and after the infusion of hypertonic saline at increasing infusion rates. Sodium and water balance were impaired. We found decreased urinary concentrating ability in situations in which endogenous (thirst or infusion of hypertonic saline) or exogenous plasma antidiuretic hormone was increased. Solute-free water formation, measured during the infusion of hypotonic saline showed normal transport in the thick ascending limb. Aquaporin-2 (AQP2) expression was measured by Western blot to evaluate water permeability in collecting ducts. We found that Al produced downregulation of AQP2 in plasma membranes and intracellular vesicles, that could account for the impaired water handling. Administration of desmopressin increased AQP2 in plasma membranes, suggesting that Al did not impair trafficking of this protein, but could interfere with AQP2 synthesis.

Alterations of the renal function and oxidative stress in renal tissue from rats chronically treated with aluminium during the initial phase of hepatic regeneration.

Various indices of renal functions during the early stage of hepatic injury were studied in rats chronically treated with aluminum (Al) lactate. Tubular and hemodynamic parameters were analyzed four days after producing a 65% partial hepatectomy (PH). Water and sodium balances were also studied. Oxidative stress and the activity of Na-K-ATPase were determined in renal tissue. The rats were distributed in four groups: control, Al, PH, Al+PH. Al did not modify the hemodynamic renal functions and the PH-group reduced the glomerular filtrate rate (GFR). The Al + PH group presented a decrease in the renal blood flow and accentuated the GFR fall as compared with PH. The fractional excretion (FE) of water and sodium increased in the PH group. The rats chronically treated with Al and then submitted to the PH protocol developed a further increase in FE of water but a reduction in FE of sodium. Both PH and Al promoted an increase in the aldosterone. PH and Al induced a similar increase of the lipoperoxidation status with reduction of glutathione (GSH) and the activity of glutathione peroxidase (GSH-Px). The data indicated that Al is an inhibitor of catalase. The GSH and GSH-Px activity in the Al + PH group demonstrated a synergic effect of Al and PH. This work demonstrates that rats treated chronically with Al and submitted to another injury (such as hepatic damage) can aggravate renal functions, probably by increasing the oxidative state, at least in kidneys.

Losartan reverses fibrotic changes in cortical renal tissue induced by ischemia or ischemia-reperfusion without changes in renal function.

Unilateral renal ischemia for 40 min in rat results in increased fibronectin (FN) expression in proximal tubular cells. This study examines the role of 24 h of blood reperfusion and the role of the renin-angiotensin system (RAS) on these results. Rats were submitted to 40 min of unilateral renal ischemia followed by 24 h of blood reperfusion. Renal function was assayed by clearance measurement in metabolic cages. Intracellular ATP and calcium were determined in proximal tubules. The expression and abundance of FN were investigated by reverse transcription-polymerase chain reaction, ELISA and Western blot either in isolated proximal tubules or cortex homogenates from control, ischemic and ischemic with reperfusion rats. Matrix metalloproteases (MMPs) activity was also measured. Losartan effects on renal function and on the abundance of FN and the MMPs activity in cortical homogenates were also measured. The renal function remained altered after 24 h of reperfusion in untreated and losartan-treated ischemic rats. On the other hand, the abundance of FN is increased after reperfusion both in isolated proximal tubules and total cortex homogenates and the same pattern was observed in the MMPs activity. Twenty-four h of blood reperfusion presented FN-mRNA signals similar to control ones. Losartan pretreated-rats presented diminished FN abundance in homogenates of cortex tissue from ischemic rats with or without reperfusion. Similar results were observed in the MMPs-activity. These results suggest that angiotensin II acting via the AT1 receptor plays a role in the development of tubulointersticial fibrosis after ischemia-reperfusion by activation of intrarenal RAS from the injured kidney.

Effects of aluminum on phosphate metabolism in rats: a possible interaction with vitamin D3 renal production.

The effect of chronic aluminum (Al) administration on the phosphorous (Pi) metabolism of different target tissues was studied. Male Wistar rats received aluminum lactate for 3 months (5.75 mg/kg bodyweight of Al, i.p., three times per week). The animals were studied at the end of the 1st, 2nd and 3rd month of treatment. They were housed individually in metabolic cages for 4 days to study Pi and calcium (Ca) balance. Daily food and water intakes were recorded for all animals and urine and feces were collected for Pi and calcium assays. After 3 months the Pi intestinal absorption and the Pi deposition in bone were studied using 32Pi. Another group of rats was treated daily for 7 days with calcitriol (0.08 microg/kg body weight in sesame oil, i.p.) and the Pi balance was studied for the last 4 days. The results indicated that chronic administration of Al affected simultaneously the Pi and calcium balance, with a significant diminution of calcium and increased Pi accretion in bones, together with a diminution in the intestinal absorption of Pi. The treatment of the rats with calcitriol promoted a normalized Pi balance in Al treated rats. These findings suggest that Al could modify the Pi metabolism acting directly on intestine, kidney and bone, or indirectly through possible changes in the levels of vitamin D3.

Effect of chronic accumulation of aluminum on renal function, cortical renal oxidative stress and cortical renal organic anion transport in rats.

The aim of the present work was to study the nephrotoxicity of aluminum lactate administered for 3 months (0.57 mg/100 g bodyweight aluminum, i.p., three times per week) to male Wistar rats. Renal function was studied after 6 weeks of treatment (urine was obtained from rats in metabolic cages) and at the end of the treatment using clearance techniques. Another group of rats was used as kidneys donors at the end of treatment. The renal cortex was separated and homogenized to determine glutathione (GSH) level, glutathione S-transferase (GST) activity and lipid peroxidation (LPO) level. Renal cortex slices were also used to study the p-aminohippuric acid (PAH) accumulation during steady-state conditions and the kinetics of uptake process. Clearance results, at the end of the treatment, indicated that renal functions in treated-rats were not different from those measured in control rats, although the renal concentration parameters differ when they were measured in treated rats after 24 h of food and water deprivation. Balances of water and sodium were also modified at both 1.5 and 3 months of treatment. The activity of alkaline phosphatase (AP) relative to inulin excreted in urine was significantly impaired: controls 2.2+/-0.6 IUI/mg, Al-treated 5.1+/-0.5 IU/mg, P<0.05. These data indicated that proximal tubular cells were loosing apical brush border membranes. Data obtained in cortex homogenates indicated that both GSH and GST activity were significantly decreased, and a significant increase of LPO was noted simultaneously in Al-treated rats. Renal accumulation of PAH, estimated as slice-to-medium ratio, decreased significantly in the Al-treated rats: control rats 3.06+/-0.02 ( n=12), Al-treated rats 2.26+/-0.04 ( n=12), P<0.0001. The maximal rate of uptake was also diminished in treated rats, while the apparent affinity remained unchanged. All these results indicate that aluminum accumulation in renal tissue affects cellular metabolism, promotes oxidative stress and induces alterations in renal tubular PAH transport, together with an impairment in sodium and water balance only detected under conditions of water deprivation, without other evident changes in glomerular filtration rate or other global functions measured by clearance techniques at least at this time of chronic toxicity.

Rat renal function four days after bile-duct ligation: effects of indomethacin and vasoactive agents.

The purpose of this study was to assess the effects of the cyclooxygenase inhibitor, indomethacin, and some vasoactive agents on the renal functional parameters during the early liver injury induced by four days bile duct ligation (BDL). Wistar rats with four days-BDL and control-sham operated were used. Renal function was measured in anesthetized rat treated with a single dose of indomethacin (control, 0.3, 1.0, 3.0 mg/kg b.w.; i.v.) one hour before clearance studies. Sulindac effects were also evaluated (5 mg/kg b.w., i.p). Isolated rat kidney preparations from control and BDL donor rats were used to study renal vascular response to noradrenaline, carbachol or sodium nitroprusside. The bile duct ligation promoted a diminished renal cortical plasma flow (RCPF) on the fourth day post surgery accompanied with a diminution in the glomerular filtration rate (GFR), increased filtration fraction and increased fractional excretion of water and sodium. Indomethacin 0.3 mg/kg induced an increase in GFR and RCPF, maintaining the high filtration fraction in BDL rats. The other doses did not alter these parameters as compared with bile duct ligated rats without treatment, but indomethacin 3 mg/kg caused a significant increase in filtration fraction. Indomethacin induced dose-dependent diminution in natriuresis in sham and BDL groups. Sulindac did not modify hemodynamic parameters, but induced antinatriuresis and antidiuresis in both experimental groups. Maximal vascular responses to noradrenaline measured in isolated rat kidneys were statistically diminished in BDL-rats as compared with controls (C, n=7; 35.0+/-2.3 mmHg ml(-1) min; BDL-rats, n=5; 23.8+/-0.7 mmHg ml(-1) min; p<0.02), without changes in EC15. Maximal relaxation induced by sodium nitroprusside in the phenylephrine (PHE)-pre-constricted renal vasculature in control preparations did not differ from that observed in BDL group (C: n=6; 49.5+/-2.3%). Values of EC50 were 1.26+/-0.07 microM (n=6) in control preparations and 0.34+/-0.03 microM (n=4) in kidneys from BDL-rats (p<0.001). Carbachol induced a biphasic relaxation of PHE-pre-constricted renal vasculature. No differences in maximal responses were found. EC50 value of the second phase in BDL group was significantly decreased compared to control preparations (C: n=6, 0.47+/-0.05 microM; BDL: n=6, 0.22+/-0.03 microM p<0.001). The present results show that the altered renal function after a short time post bile duct ligation is determined, at least in part, by increased release of arachidonic derivatives in vascular bed and tubular cells. At this stage of liver injury, the alteration in the renal vascular response to different vasoactive agents is remarkable.