THE ROLE OF ANGIOTENSIN AT1 RECEPTORS IN THE DIURETIC, NATRIURETIC, KALIURETIC AND BLOOD-PRESSURE RESPONSES INDUCED BY ANGIOTENSIN-II ACTIVATION OF THE MEDIAN PREOPTIC NUCLEUS IN CONSCIOUS RATS

We determined the effects of two classical angiotensin II (ANG II) antagonists, [Sar(1), Ala(8)]-ANG II and [Sar(1), Thr(8)]-ANG II, and losartan (a nonpeptide and selective antagonist for the AT 1 angiotensin receptors) on diuresis, natriuresis, kaliuresis and arterial blood pressure induced by ANG II administration into the median preoptic nucleus (MnPO) of male Holtzman rats weighing 250-300 g. Urine was collected in rats submitted to a water load (5% body weight) by gastric gavage, followed by a second water load (5% body weight) 1 h later. The volume of the drug solutions injected was 0.5 mu l over 10-15 s. Pre-treatment with [Sar(1), Ala(8)]-ANG II (12 rats) and [Sar(1), Thr(8)]-ANG II (9 rats), at the dose of 60 ng reduced (13.7 +/- 1.0 vs 11.0 +/- 1.0 and 10.7 +/- 1.2, respectively), whereas losartan (14 rats) at the dose of 160 ng totally blocked (13.7 +/- 1.0 vs 7.6 +/- 1.5) the urine excretion induced by injection of 12 ng of ANG II (14 rats). [Sar(1), Ala(8)]-ANG II impaired Na+ excretion (193 +/- 16 vs 120 +/- 19): whereas [Sar(1), Thr(8)]-ANG II and losartan blocked Na+ excretion (193 +/- 16 vs 77 +/- 15 and 100 +/- 12, respectively) induced by ANG II. Similar effects induced by ANG II on K+ excretion were observed with [Sar(1), Ala(8)]-ANG II, [Sar(1), Thr(8)]-ANG II, and losartan pretreatment (133 +/- 18 vs 108 +/- 11, 80 +/- 12, and 82 +/- 15, respectively). The same doses as above of [Sar(1), Ala(8)]-ANG II (8 rats), [Sar(1), Thr(8)]-ANG II (8 rats). and losartan (9 rats) blocked the increase in the arterial blood pressure induced by 12 ng of ANG II (12 rats) (32 +/- 4 ru 4 +/- 2, 3.5 +/- 1, and 2 +/- 1: respectively. The results indicate that the AT1 receptor subtype participates in the increases of diuresis, natriuresis. kaliuresis and arterial blood pressure induced by the administration of ANG II into the MnPO.

PROGESTERONE ADMINISTRATION TO OVARIECTOMIZED RATS REDUCES WATER AND SALT INTAKE INDUCED BY CENTRAL ADMINISTRATION OF ANGIOTENSIN-II

We tested the effects of estradiol, progesterone and testosterone on water and salt intake induced by angiotensin II (ANG II) injected into the third ventricle of female Holtzman rats weighing 250-300 g. The water and salt ingestion observed after 120 min in the control experiments (injection of 0.5 mu l of 0.15 M NaCl into the third ventricle) was 1.6 +/- 0.3 ml (N = 10) and 0.3 +/- 0.1 ml (N = 8) in intact rats, respectively, and 1.4 +/- 0.3 ml (N = 10) and 0.2 +/- 0.1 (N = 8) in ovariectomized rats, respectively. ANG II injected in intact rats (4, 6, 12, 25, and 50 ng, icv, in 0.5 mu l saline) induced an increase in water intake (4.3 +/- 0.6, 5.4 +/- 0.7. 7.8 +/- 0.8, 10.4 +/- 1.2, 11.2 +/- 1.4 ml/120 min, respectively) (N = 43). The same doses of icv ANG II in intact rats increased the 3% NaCl intake (0.9 +/- 0.2; 1.4 +/- 0.3, 2.3 +/- 0.4, 2.2 +/- 0.3. and 2.5 +/- 0.4 ml/120 min, respectively) (N = 42). When administered to ovariectomized rats ANG II induced comparable amounts of water intake (4.0 +/- 0.5, 4.8 +/- 0.6, 6.9 +/- 0.7. 9.6 +/- 0.8, and 10.9 +/- 1.2 ml/120 min, respectively) (N = 43) but there was a significant decrease of 3% NaCl solution ingestion (0.3 +/- 0.1, 0.4 +/- 0.1, 0.8 +/- 0.2, 0.7 +/- 0.2, and 0.6 +/- 0.2 ml/120 min, respectively) (N = 44). Estrogen (50 mu g), progesterone (25 ng), and testosterone (300 mu g) were injected daily into ovariectomized rats for 21 days. Treatment with estrogen decreased the water intake and abolished the saline ingestion induced by icy injection of ANG II (12 ng (2.8 +/- 1.2 and 0.3 +/- 0.1 ml/120 min, respectively) (N = 8). Treatment with progesterone also reduced the water intake (3.3 +/- 0.6 ml/120 min) (N = 8) and abolished the ANG II-induced saline ingestion (0.4 +/- 0.1 ml/120 min) (N = 8), but these effects were not observed with testosterone (6.4 +/- 0.8 and 2.2 +/- 0.3 ml/120 min, respectively) (N = 8). These results indicate that ANG II induces a greater increase in sodium intake in intact female rats than in ovariectomized rats and that estrogen and progesterone impair water and sodium intake in ovariectomized rats.

Síntese e aplicação de sílica mesoporosa modificada com o ligante 4-amino-2-mercaptopirimidina na pré-concentração de Cd (II), Cu(II), Pb(II), Zn(II) e Ni(II) em amostras de águas naturais

Pós-graduação em Ciência e Tecnologia de Materiais - FC

Application of mesoporous SBA-15 silica functionalized with 4-amino-2-mercaptopyrimidine for the adsorption of Cu(II), Zn(II), Cd(II), Ni(II), and Pb(II) from water

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of injection of L-NAME on drinking response

The drinking behavior responses to centrally administered NG-nitro-L-arginine methyl ester (L-NAME; 10, 20 or 40 µg/µl), an inhibitor of nitric oxide synthase, were studied in satiated rats, with cannulae stereotaxically implanted into the lateral ventricle (LV) and subfornical organ (SFO). Water intake increased in all animals after angiotensin II (ANG II) injection into the LV, with values of 14.2 ± 1.4 ml/h. After injection of L-NAME at doses of 10, 20 or 40 µg/µl into the SFO before injection of ANG II (12 ng/µl) into the LV, water intake decreased progressively and reached basal levels after treatment with 0.15 M NaCl and with the highest dose of L-NAME (i.e., 40 µg). The water intake obtained after 40 µg/µl L-NAME was 0.8 ± 0.01 ml/h. Also, the injection of L-NAME, 10, 20 or 40 µg/µl, into the LV progressively reduced the water intake induced by hypertonic saline, with values of 5.3 ± 0.8, 3.2 ± 0.8 and 0.7 ± 0.01 ml/h, respectively. These results indicate that nitric oxide is involved in the regulation of drinking behavior induced by centrally administered ANG II and cellular dehydration and that the nitric oxide of the SFO plays an important role in this regulation.

Paraventricular nucleus administration of DuP753 or PD123319 inhibits the effects of angiotensin on water and sodium intake

We determined the effects of DuP753 and PD123319 (both nonpeptides and selective antagonists of the AT(1) and AT(2) angiotensin receptors, respectively), and [Sar(1), Ala(8)]ANG II (a non-selective peptide antagonist of angiotensin receptors) on water and 3%NaCl intake induced by administration of angiotensin II (ANG II) into the paraventricular nucleus (PVN) of sodium-depleted Holtzman rats weighing 250-300 g. Twenty hours before the experiments, the rats were depleted of sodium using furosemide (10 ng/rat, sc). The volume of drug solution injected was 0.5 mu l over a period of 10-15 sec. Water and sodium intake were measured at 0.25, 0.5, 1.0 and 2.0 h. Pre-treatment with DuP753 (14 rats) at a dose of 60 ng completely abolished the water intake induced by injection of 12 ng of ANG II (15 rats) (6.4 +/- 0.6 vs 1.4 +/- 0.3 ml/2 h), where [Sar(1), Ala(8)]ANG II (12 rats) and PD123319 (10 rats) at the doses of 60 ng partially blocked water intake (6.4 +/- 0.6 vs 2.9 +/- 0.5 and 2.7 +/- 0.2 ml/2 h, respectively). In the same animals, [Sar(1), Ala(8)]ANG II, DuP753, and PD123319 blocked the sodium intake induced by ANG II (9.2 +/- 1.6 vs 3.3 +/- 0.6, 1.8 +/- 0.3, and 1.4 +/- 0.2 ml/2 h, respectively). These results indicate that both DuP753 and PD123319, administered into the PVN, blocked the water and sodium intake induced by administration of ANG II into the same site.

Functional evidence that the central renin-angiotensin system plays a role in the pressor response induced by central injection of carbachol

We investigated the effects of losartan, an AT 1-receptor blocker, and ramipril, a converting enzyme inhibitor, on the pressor response induced by angiotensin II (ANG II) and carbachol (a cholinergic receptor agonist). Male Holtzman rats (250-300 g) with a stainless steel cannula implanted into the lateral ventricle (LV) were used. The injection of losartan (50 nmol/l μl) into the LV blocked the pressor response induced by ANG II (12 ng/l μl) and carbachol (2 nmol/l μl). After injection of ANG II and carbachol into the LV, mean arterial pressure (MAP) increased to 31 ± 1 and 28 ± 2 mmHg, respectively. Previous injection of losartan abolished the increase in MAP induced by ANG II and carbachol into the LV (2 ± 1 and 5 ± 2 mmHg, respectively). The injection of ramipril (12 ng/l μl) prior to carbachol blocked the pressor effect of carbachol to 7 ± 3 mmHg. These results suggest an interaction between central cholinergic pathways and the angiotensinergic system in the regulation of arterial blood pressure.

Scanning electron microscopic evaluation of the root apex of mandibular premolars.

This aim of this study was to evaluate the root apex of mandibular premolars regarding the presence of main and accessory foramina. The root apexes from fifty extracted mandibular single-rooted premolars were examined by scanning electron microscopy (SEM). The apical openings had their diameter measured and were identified as main or accessory foramina. Double blinded and calibrated examiners analyzed the SEM photographs and classified the premolar roots into three types, based on the presence and size of the apical openings. Type I: roots with a single main apical foramen and no accessory foramina; type II: roots with a main foramen and one or more accessory foramina; type III: roots with accessory foramina only. For the first premolar, 16 roots were classified as type I (48.48%), 4 as type II (12.12%) and 13 as type III (39.40%). For the second premolars, 10 roots were classified as type I (58.83%), 3 as type II (17.65%) and 4 as type III (23.52%). The high incidence of roots with accessory foramina only (type III), mainly in the first premolar, warns of the need for caution during working length determination and apical debridement.

Validação fisiológica da dosagem dos metabólitos de glucocorticóides em fezes de Papagaio-verdadeiro (Amazona aestiva)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Efeito do benzoato de estradiol na recuperação de oócitos, embriões e nos parâmetros hematológicos de cadelas recém acasaladas

We investigated estradiol benzoate effects on oocytes/embryos recovery rate and the influence of this drug on the hematopoietic system. Twenty four bitches were divided in two groups, Group I, 12 females that received a single shot of estradiol benzoate, 0.2 mg/kg intramuscularly, between 2 and 7 days after the date of the last mismating or insemination and, Group II (control), 12 bitches that received 0.2 ml/kg of oily diluent, in corresponding dates. The bitches were ovary-hysterectomized and the uterus/oviduct were isolated and flushed with a PBS, heparin and polyvinyl alcohol solution. Oocytes and embryos were quantified and classified according to their stage of development. Blood counts were performed on M1 (before drug administration), M2 (15 days after drug administration) and M3 (40 days after drug administration). Pearson correlation coefficient was used to analyze the variable retrieval structures, while Fisher exact test was used for the analysis of embryonic viability. ANOVA was used to analyze repeated measurements and Tukey test for hematological parameters. All tests were performed at 5% significance level. The recovery rate of total structures in group I was lower (22.88%) than group II (65.85%). A lower embryo recovery (ratio 3: 52) rate and a greater number of degenerated structures (ratio 11: 1) were observed in group I. Hematological parameters showed significant difference in erythrocytes, hematocrit and hemoglobin concentrations 15 days after drug administration and difference in leukocytes concentration 40 days after using the medication in bitches of group I, however, at the end of the experiment all bitches had blood counts considered normal.

An electroanalytical application of 2-aminothiazole-modified silica gel after adsorption and separation of Hg(II) from heavy metals in aqueous solution

2-Aminothiazole covalently attached to a silica gel surface was prepared in order to obtain an adsorbent for Hg(II) ions having the following characteristics: good sorption capacity, chemical stability under conditions of use, and, especially, high selectivity. The accumulation voltammetry of mercury(II) was investigated at a carbon paste electrode chemically modified with silica gel functionalized with 2-aminothiazole (SIAMT-CPE). The repetitive cyclic voltammogram of mercury(II) solution in the potential range -0.2 to + 0.6 V versus Ag/AgCl (0.02 mol L-1 KNO3; V = 20 mV s(-1)) show two peaks one at about 0.1 V and other at 0.205 V. The anodic wave peak at 0.205 V is well defined and does not change during the cycles and it was therefore further investigated for analytical purposes using differential pulse anodic stripping voltammetry in differents supporting electrolytes. The mercury response was evaluated with respect to pH, electrode composition, preconcentration time, mercury concentration, cleaning solution, possible interferences and other variables. The precision for six determinations (n = 6) of 0.02 and 0.20 mg L-1 Hg(II) was 4.1 and 3.5% (relative standard deviation), respectively. The detection limit was estimated as 0.10 mu g L-1 mercury(II) by means of 3:1 current-to-noise ratio in connection with the optimization of the various parameters involved and using the highest-possible analyser sensitivity. (c) 2006 Elsevier Ltd. All rights reserved.

Reduction capability of soil humic substances from the Rio Negro basin, Brazil, towards Hg(II) studied by a multimethod approach and principal component analysis (PCA)

This paper characterizes humic substances (HS) extracted from soil samples collected in the Rio Negro basin in the state of Amazonas, Brazil, particularly investigating their reduction capabilities towards Hg(II) in order to elucidate potential mercury cycling/volatilization in this environment. For this reason, a multimethod approach was used, consisting of both instrumental methods (elemental analysis, EPR, solid-state NMR, FIA combined with cold-vapor AAS of Hg(0)) and statistical methods such as principal component analysis (PCA) and a central composite factorial planning method. The HS under study were divided into groups, complexing and reducing ones, owing to different distribution of their functionalities. The main functionalities (cor)related with reduction of Hg(II) were phenolic, carboxylic and amide groups, while the groups related with complexation of Hg(II) were ethers, hydroxyls, aldehydes and ketones. The HS extracted from floodable regions of the Rio Negro basin presented a greater capacity to retain (to complex, to adsorb physically and/or chemically) Hg(II), while nonfloodable regions showed a greater capacity to reduce Hg(II), indicating that HS extracted from different types of regions contribute in different ways to the biogeochemical mercury cycle in the basin of the mid-Rio Negro, AM, Brazil. (c) 2007 Published by Elsevier B.V.

Estudo da labilidade de Cu(II), Cd(II), Mn(II) e Ni(II) em substâncias húmicas aquáticas utilizando-se membranas celulósicas organomodificadas

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Dynamics and Heterogeneity of Pb(II) Binding by SiO2 Nanoparticles in an Aqueous Dispersion

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)