Plasma extravasation mediated by lipopolysaccharide-induction of kinin B1 receptors in rat tissues.

The present study was performed to: (a) evaluate the effects of kinin B1 (Sar[D-Phe8]-des-Arg9-BK; 10 nmol/kg) and B2 (bradykinin (BK); 10 nmol/kg) receptor agonists on plasma extravasation in selected rat tissues; (b) determine the contribution of a lipopolysaccharide (LPS) (100 microg/kg) to the effects triggered by B1 and B2 agonists; and (c) characterize the selectivity of B1 ([Leu8]desArg9-BK; 10 nmol/kg) and B2 (HOE 140; 10 nmol/kg) antagonists as inhibitors of this kinin-induced phenomenon. B1 and B2 agonists were shown to increase plasma extravasation in the duodenum, ileum and also in the urinary bladder of the rat. LPS pretreatment enhanced the plasma extravasation mediated only by the B1 agonist in the duodenum, ileum, trachea, main and segmentar bronchi. These effects were prevented by the B1. but not the B2 antagonist. In normal rats, the B2 antagonist inhibited the effect of B2 agonist in all the tissues analyzed. However, in LPS-treated rats, the B2 antagonist was ineffective in the urinary bladder. These results indicate that kinins induce plasma extravasation in selected rat tissues through activation of B1 and B2 receptors, and that LPS selectively enhances the kinin effect on the B1 receptor in the duodenum, ileum, trachea and main and segmentar bronchi, and may increase B1 receptor expression in these tissues.

Effect of quercetin on tachykinin-induced plasma extravasation in rat urinary bladder.

The effect of quercetin on substance P-induced plasma extravasation in rat urinary bladder and its modulation by endogenous peptidases in conscious rats was studied. Plasma protein extravasation (PE) was assayed by measurement of extravasated Evans blue dye (microg/g dry tissue). Intravenous injection of substance P (SP, 10 nmol/kg) significantly increased PE in the urinary bladder. PE evoked by SP was increased significantly by quercetin (20 mg/kg, p.o.) pretreatment in the urinary bladder (73.5 +/- 4.9 to 152.2 +/- 9.9). Pretreatment with captopril, an angiotensin-converting enzyme (ACE) inhibitor (10 nmol/kg, i.v.), or with phosphoramidon, a neutral endopeptidase (NEP) inhibitor (2.5 micromol/kg, i.v.) also potentiated the SP-induced PE in urinary bladder, 286.2 +/- 20.4 and 323.3 +/- 34.0, respectively. Quercetin did not show any effect on neurokinin-A (NKA, 10 nmol/kg, i.v.) -induced plasma extravasation. The present study demonstrates that quercetin potentiates the PE induced by substance P in the urinary bladder. These effects suggest that this flavonoid might cause inhibition of NEP and/or ACE.

Synaptosomal glutamate release induced by the fraction Bc2 from the venom of the sea anemone Bunodosoma caissarum.

The effect of a fraction (Bc2) from the venom of the sea anemone Bunodosoma caissarum on [3H]glutamate release from rat cortical synaptosomes was investigated. Bc2 (2-20 microg/ml) provoked massive glutamate release without causing synaptosome disruption. Glutamate release stimulated by Bc2 was independent of extracellular Ca2+ and of voltage-sensitive Na+ channels, and it was completely abolished by the addition of sphingomyelin. No definitive evidence about the mechanism underlying the stimulatory effect of Bc2 is available as yet. However, a direct interaction with the exocytotic machinery cannot be ruled out.

Valor del isómero dextrógiro del ácido láctico sérico en la isquemia intestinal en ratas / Value of serum d-lactate levels during intestinal isquemia in rats

El D-lactato fue estudiado in vitro como marcador de isquemia intestinal asociada a la presencia de bacterias patógenas en el intestino de ratas. En un estudio in vitro se correlacionó la producción de D-lactato con el crecimiento de dos cepas de E coli. En el estudio in vivo se utilizaron 100 ratas Wistar de 250a 300 gr divididos en ausencia y presencia de isquemia intestinal. Los resultados in vitro demostraron que la producción de D-lactato es acumulativa. Los resultados in vivo demostraron que el nivel sérico de D-lactato dependió de la concentración bacteriana intraluminal y no de la gravedad de la isquemia. Cuando ambas variables fueron asociadas, se produjo un efecto sinérgico en la elevación sérica de D-lactato, mayor en comparación a cada variable aislada. Se observaron resultados similares con la flora natural con o sin isquemia intestinal. Basados en los datos obtenidos, los niveles de D-lactato sérico parecen tener un rol potencial como marcador de isquemia intestinal, cuando se agrega la presencia de bacterias en la luz intestinal

Valor del isómero dextrógiro del ácido láctico sérico en la isquemia intestinal en ratas / Value of serum d-lactate levels during intestinal isquemia in rats

El D-lactato fue estudiado in vitro como marcador de isquemia intestinal asociada a la presencia de bacterias patógenas en el intestino de ratas. En un estudio in vitro se correlacionó la producción de D-lactato con el crecimiento de dos cepas de E coli. En el estudio in vivo se utilizaron 100 ratas Wistar de 250a 300 gr divididos en ausencia y presencia de isquemia intestinal. Los resultados in vitro demostraron que la producción de D-lactato es acumulativa. Los resultados in vivo demostraron que el nivel sérico de D-lactato dependió de la concentración bacteriana intraluminal y no de la gravedad de la isquemia. Cuando ambas variables fueron asociadas, se produjo un efecto sinérgico en la elevación sérica de D-lactato, mayor en comparación a cada variable aislada. Se observaron resultados similares con la flora natural con o sin isquemia intestinal. Basados en los datos obtenidos, los niveles de D-lactato sérico parecen tener un rol potencial como marcador de isquemia intestinal, cuando se agrega la presencia de bacterias en la luz intestinal

In vitro study of enamel erosion caused by soft drinks and lemon juice in deciduous teeth analysed by stereomicroscopy and scanning electron microscopy.

The erosion caused in vitro by cola-type and guaraná-type beverages (the latter is a soft drink sold in Brazil), and a canned lemon juice on the enamel of human deciduous teeth was analyzed. Morphological analysis of affected enamel was done using stereomicroscopy and scanning electron microscopy (SEM). The harmful effect of all test products on deciduous enamel was clearly demonstrated. Stereomicroscopy showed loss of gloss and an alteration in normal color of enamel, with irregular loss of dental tissue in variable degrees. Such a loss became more serious as the time of incubation increased. Different degrees of solubilization of enamel prisms were demonstrated by SEM, affecting initially the sheaths and the heads of prisms and later their tails. Areas of erosion increased in proportion to the time of incubation. All the products showed a great erosive potential on human deciduous dental enamel.

Raman and infrared studies on the conformation of porcine pancreatic and Crotalus durissus terrificus phospholipases A2.

Raman and infrared spectroscopies were used to investigate conformational features of Crotalus durissus terrificus and porcine pancreatic phospholipases A2, as well as the proenzyme of the latter. The results indicate that conformational changes occur for the phospholipase molecules as a consequence of different experimental conditions such as change of physical state, presence of certain ionic species and interaction with a model substrate analog. Amorphous and crystalline solid phospholipase present discrepant conformational features. Conformational transitions were detected for the pancreatic zymogen----phospholipase A2 transformation and different secondary contents were observed for a toxic and a nontoxic form of the phospholipase molecule. All those structural changes have been shown to involve primarily the architecture of the polypeptide backbone rather than the conformation of amino acid residue side-chains. Disulfide bridges have shown consistently a gauche-gauche-gauche geometry which has not been disturbed by any of the experimental conditions employed. The external occurrence of tryptophan residues has been a common feature for the systems assayed, as well as the predominant localization of tyrosine residues in hydrophilic environment, probably at the molecular surface.