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The Muscovy duck is a commercially important bird on the island of Marajó usually raised in a peculiar system that includes supplying fish viscera to the birds under semi-extensive farming conditions. This enables a risk of contamination and losses in the production of these birds, resulting from injuries caused by helminth infections, especially nematodes. The objective of this study was to evaluate the histopathological changes caused by nematodes of the genera: Eucoleus, Anisakis and Contracaecum. Thirty-three ducks with lesions in the esophagus and ventricle were analyzed. Histopathological exams showed a mild inflammatory infiltrate in the submucosa of the esophagus caused by the fixation of E. contortus and third stage larvae of Anisakis sp., and we recorded third stage larvae of Contracaecum sp. parasitizing the ventricle, this being the first record of this parasite in ducks in Brazil.(AU)

O pato doméstico é uma ave amplamente comercializada na Ilha de Marajó, com um peculiar manejo que inclui a oferta de vísceras de peixes aos animais em criações semiextensivas, propiciando, assim, risco de contaminação e perdas na produção dessas aves decorrentes de lesões oriundas de infecções por helmintos, especialmente os nematódeos. Nesse sentido, objetivou-se avaliar as alterações histopatológicas causadas por nematódeos dos gêneros: Eucoleus, Anisakis e Contracaecum. Foram analisados 33 patos, e três exemplares apresentaram lesões no esôfago e no ventrículo. Exames histopatológicos demonstraram discreto infiltrado inflamatório na submucosa do esôfago ocasionado pela fixação de E. contortus e larvas de terceiro estágio de Anisakis sp., bem como foram registradas larvas de terceiro estágio de Contracaecum sp. parasitando o ventrículo, sendo esse o primeiro registro desse parasito em patos no Brasil.(AU)

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In the present study, a practical activity is proposed to adopt an experimental approach to demonstrate the relationship between the equilibrium potential for K(+) and transmembrane electrical potential without glass micropipettes. A conventional setup for recording contractile activity of isolated smooth muscle preparations was used based on the events elegantly described by Somlyo and Somlyo in the 1960s. They showed that, in response to a given stimulus, smooth muscle cells may contract, recruiting electromechanical or pharmacomechanical coupling by mechanisms that involve, or not, changes in transmembrane potential, respectively. By means of contractions and relaxations of a ring-like preparation from the rat mesenteric artery, it is possible to observe the functional consequences of handling K(+) concentration in the extracellular compartment and the effects caused by opening K(+) channels in that preparation, which are significant when the cell membrane establishes an electrical potential difference between intra- and extracellular compartments (driven mainly by K(+) permeability under resting conditions). The effects observed by students fit well with values predicted by Nernst and Goldman-Hodgin-Katz equations, and we demonstrated that the activity is able to improve students' comprehension regarding basic principles of bioelectricity.

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Natural intoxication of livestock by ingestion of Ipomoea asarifolia leaves has been reported to occur widely in Brazil. Previous studies carried out by our research group provided strong evidence that a lectin could be involved with the toxic properties of I. asarifolia. To reinforce this hypothesis, a lectin-enriched fraction (LEF) was isolated from I. asarifolia leaves and its toxic effects were assessed. Leaves of I. asarifolia were excised from plants growing widely in the field, mechanically wounded and maintained in a chamber at 25 ± 3 °C for 72h in the dark, under near 100% relative humidity. The leaf proteins were extracted, ammonium sulfate precipitated, chromatographed on DEAE-cellulose and Phenyl-Sepharose to produce LEF that under SDS-PAGE showed a molecular mass of 44.0 kDa and after N-terminal amino acid analysis a primary sequence composed of AGYTPVLDIGAEVLAAGEPY. The in vivo toxicity of LEF assessed by intraorbital injection in mice showed induced severe uncoordinated movements without death. LEF reduced the muscular contraction in a dose depend way and at 29.8 µg/mL (CE(50)) it produces 50% inhibition of contraction, suggesting that LEF blunts autonomic neurotransmission. Isolated rat kidneys were perfused with LEF and no effects on the perfusion pressure or renal vascular resistance were observed, but urinary flow and glomerular filtration rate increased. Moreover, the percentage of tubular transport of Na(+), K(+) and Cl(-) decreased. Histological examination of the kidneys perfused with LEF exhibited little alterations. These toxic effects observed above were concomitant with the increase of LEF hemagglutination activity, which strongly suggest that one of the toxic principles of I. asarifolia is a lectin present in its leaves.

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In the present study, the effects of Polybia paulista venom (PPV) on renal and vascular tissues were investigated. Isolated kidneys perfused with PPV (1 and 3 ìg/mL) had increased perfusion pressure, renal vascular resistance, urinary flow, and glomerular filtration rate; and reduced sodium tubular transport. Histological evaluation demonstrated deposits of proteins in Bowman's space and tubular lumen, and focal areas of necrosis. The venom promoted a cytotoxic effect on Madin-Darby canine kidney (MDCK) cells. A significant increase in lactic dehydrogenase levels was observed in response to venom exposure. In isolated mesenteric vascular beds, pressure and vascular resistance augmented in a dose-dependent manner. PPV increased the contractility of aortic rings maintained under basal tension. This contractile response was inhibited when preparations were maintained in Ca2+-free medium. Likewise, verapamil, a voltage-gated calcium channel blocker, also inhibited the contractile response. In this study, phentolamine, a blocker of á-adrenergic receptor blocker, significantly reduced the contractile effect of PPV in the aortic ring. In conclusion, PPV produced nephrotoxicity, which suggests a direct effect on necrotic cellular death in renal tubule cells. The vascular contractile effect of PPV appears to involve calcium influx through voltage-gated calcium channels via adrenergic regulation.

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In this study, we evaluated the actions of Crotalus durissus cumanensis venom (CDCmV), and its crotoxin (Crtx) fraction, on renal and vascular functions in Wistar rats. In isolated perfused kidneys, CDCmV (10 µg/mL) significantly increased the perfusion pressure (PP) from 110.7 ± 2.4 to 125.3 ± 2.8 mmHg after 30 minutes. This effect was accompanied by an increased renal vascular resistance (RVR) from 5.4 ± 0.1 to 6.2 ± 0.2 mmHg/mL.g-1.min-1. We observed decreases in urinary flow (UF) from 0.13 ± 0.01 to 0.05 ± 001 mL.g-1.min-1 and glomerular filtration rate (GFR) from 0.66 ± 0.06 to 0.18 ± 0.02 mL.g-1.min-1. Crtx did not change PP or RVR, but diminished GFR (from 0.65 ± 0.05 to 0.26 ± 003 mL.g-1.min-1) and UF (from 0.11 ± 0.008 to 0.09 ± 0.008 mL.g-1.min-1). Both CDCmV and Crtx reduced the percentage of tubular transport of sodium, chloride and potassium. The cytotoxicity of these substances against MDCK cells was tested by the MTT method: only CDCmV caused a decrease in the cell viability with an IC50 of 5.4 µg/mL. In endothelium-intact isolated aortic rings, CDCmV (0.1 to 30 µg/mL) increased the sustained phenylephrine-induced contraction to a value of 130.0 ± 6.6 percent of its corresponding control, but showed a relaxant effect in endothelium-denuded preparations. Similar results were observed in aortic rings contracted with potassium (40 mM). Crtx was ineffective in aortic ring assays. Thus, it is reasonable to suggest that the renal effects induced by the CDCmV may be due to its influence on the endothelium's ability to release factors that can alter the contractile behavior of vascular smooth muscle. In conclusion, CDCmV is toxic to kidney cells. It changes parameters of the renal function including the glomerular filtration rate, renal vascular resistance and tubular transport. The actions induced by CDCmV also involve endothelium-dependent vasoactive properties. Their effects may be only partially attributed to Crtx.

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Thalassophryne nattereri (niquim) is a venomous fish responsible for numerous accidents involving fishermen in northern and northeastern Brazil. The aim of the present investigation was to evaluate the action of antivenom on renal effects caused by Thalassophryne nattereri venom. Isolated kidneys of Wistar rats were perfused with a previously dialyzed Krebs-Henseleit solution containing 6 g% bovine serum albumin. The antivenom action was studied through perfusion pressure (PP), renal vascular resistance (RVR), urinary flow (UF) and glomerular filtration rate (GFR). The niquim venom (1 miug/mL), the antivenom alone (1 miug/mL) or the venom incubated with antivenom were added to the system 30 minutes after the beginning of each perfusion. Previous works have shown venom induced-alterations of renal function parameters. In the isolated rat Kidney, T. nattereri venom (1 miug/mL) increased the perfusion pressure and renal vascular resistance at 60, 90 and 120 minutes. UF and GFR also increased at 60, 90 and 120 minutes when compared with the control group; however, no effects were observed on the percent of sodium (% TNa more control equal 81.1 more or less 0.86; % TNa more 60 equal 78.04 more or less 1.18; % TNa more 90 equal -5.16 more or less 3.34; %TNa more 120 equal 79.49 more or less 0.87) and potassium (%TKcontrol equal 72.29 more or less 1.12; %TK more 60 equal 75.41 more or less 0.65; % TK more 90 equal 71.23 more or less 2.55; % TK more 120 equal 76.62 more or less 1.04) tubular transporto. The administration of the antivenom (1 miug/mL) incubated with venom (1 miug/mL) reduced the changes in PP, RVR, UF and GFR provoked by Thalassophryne nattereri venom. The group perfused with venom alone showed a moderate deposit of a proteinaceous material in the tubules and urinary space.(...)

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