S. De Moraes

Caracterização de ácidos húmicos de diferentes origens por eletroforese capilar de zona

The purpose of this work was characterization humic acids (HA) of different origins by capillary zone electrophoresis (CZE). The influence of the concentration of borate in the characterization was investigated. The results show the potential of CZE for the characterization of different HA samples, thus HA of different origins can be rapidly characterized. The characterization of HA are due to difference charge-to-size ratios and the various structural properties of the individual components caused by their different origins.

Effects of Sammarium on the Contractile Response of the Isolated Guinea Pig Ileum to Acetylcholine, Histamine, Potassium and Barium

The effects of sammarium (Sm3+) on drug responsiveness of the isolated guinea pig ileum were studied. The lanthanid at the concentration of 2x10(-4) M reduced responsiveness to acetylcholine, histamine and submaximal concentrations of potassium. The maximum response to potassium and the responsiveness to barium remained unaffected. 2x10(-3) M Sm3+ reduced barium-induced contractions and smooth muscle response to potassium Ringer. Equipotent submaximal concentration of acetylcholine, histamine, potassium and barium were analysed in order to try to establish a Sm3+-induced differential reduction in smooth muscle responvisiveness. The lanthanid imparied tissue responsiveness to acetylcholine, histamine and potassium, but did not alter reponsiveness to barium. The results seem to be consistent with the hypothesis that in the guinea pig ileum responsivenesses to acetylcholine, histamine and potassium are, probably, supported by a calcium store(s) located at the cell membrane. The persistence of responsiveness to barium could indicated that this agonist acts upon a cellular calcium store(s) insensitive to Sm3+.