O mecanismo do efeito sedativo da clonidina (CLO), um agonista α2-adrenérgico não é claro. Como a ativação dos receptores α2-adrenérgicos induz a liberação de Óxido Nítrico (NO) das células endoteliais, testamos a hipótese de que o efeito sedativo e antinociceptivo da CLO sistêmica dependeria de mecanismos relacionados a via NOGMPc. O 7-NI reduziu significativamente o tempo de sono induzido pela clonidina. O tempo de sono induzido pelo tiopental (TST) foi aumentado pela CLO, α-metildopa, rilmenidina (RIL) and midazolam. O L-NAME reduziu o prolongamento do TST da CLO, α-metildopa, RIL, sem alterar o efeito do midazolam. O efeito inibitório do L-NAME no prolongamento do TST com a CLO foi revertido pela L-arginine. Os resultados sugerem mecanismos NO-dependentes no efeito sedativo da clonidina. Esses efeitos parecem ser específicos para a ação sedativa dos agonistas α2-adrenérgicos. Avaliamos também a possível ligação envolvendo opóides e a via do NO-GMPc no efeito antinociceptivo da CLO. O efeito antinociceptivo induzido pela administração sistêmica de CLO e RIL foi avaliado utilizando o teste das contorções abdominais em camundongos e o teste tailflick. A CLO (3120 g/kg) and RIL induziram efeito antinociceptivo dose-dependente no teste das contorções abdominais e TFL. O efeito antinociceptivo da CLO foi significativamente reduzido pela inibição da NO-syntase and guanylyl ciclase. O efeito da RIL também foi reduzido pelo 7-NI. O efeito antinociceptivo da morfina foi inibido pela naloxona, que não inibiu o efeito da CLO. Nossos resultados sugerem que o efeito da CLO sistêmica não envolve receptor opióide e é modulado por uma via NO-GMPc. / The mechanism of sedative effect of clonidine (CLO), an α2-adrenoceptor agonist remain unclear. As the activation of α2-adrenoceptors induces release of nitric oxide (NO) from endothelial cells, which has led us to test the hypothesis that sedative and antinociceptive effect from systemic CLO depends on the NO-cGMP pathway mechanisms. The sleeping time in rats induced by CLO was significantly decreased by 7-NI. Thiopental sleeping time (TST) was increased by CLO, α-methyldopa, rilmenidine (RIL) and midazolam. L-NAME reduced the prolongation effect of clonidine, α-methyldopa, RIL, but did not alter the effect of midazolam on the TST. The inhibitory effect of L-NAME on CLO -dependent prolongation of TST was reversed by L-arginine. These results suggest that NO-dependent mechanisms are involved in the sedative effect of CLO. In addition, this effect seems to be specific for the sedative action of α2-adrenoceptors agonists. The possible involvement of an opioid and NO-GMPc pathway link in the antinociceptive effect of CLO was also evaluated. The antinociceptive effect induced by systemic administration of CLO and rilmenidine (RIL) was evaluated using the mice writhing tests and TFL. CLO (3120 g/kg) and RIL induces a dose-dependent antinociceptive effect in the writhing tests and TFL. The antinociceptive effect of CLO was significantly reduced by NO-synthase and guanylyl cyclase inhibition. RIL effect was also reduced by 7-NI.The antinociceptive effect of morphine, but not CLO, was inhibited by naloxone. Our current results suggest that the antinociceptive effect of systemic clonidine does not involve the opioid receptor and is modulated by the NO-cGMP pathway.

- 8 - ABSTRACT (EN) The thesis is submitted as a commented set of reviewed publications documenting and depicting the possibilities of mass spectrometry in the field of chemical, biological and pharmaceutical research; namely for the purposes of structure elucidation of selected organometallic complexes, analyses of drugs and their metabolites, monitoring of important biological markers. In course of experimental work, the following objectives were studied and solved:  Proposal and realization of micro-scale preparation of selected rhenium complexes with aromatic ligands, utilizing tetrabutyammonium tetrachlorooxorhenate as a starting material; preparation and structure characterization of oxorhenium(V) complexes with 1,2-dihydroxybenzene, 1,2,3-trihydroxybenzene, and 2,3- dihydroxynaphtalene as ligands by means of ESI/MS, APPI/MS and LDI-MS; ESI/MS and UV/Vis study of kinetic behavior of complexes arising from the reaction of tetrabutylamonnium tetrachlooxorhenate with pyrogallol and catechol as ligands. Special aim was devoted to the study of subsequent chemical transformation of primarily formed Re(V) complexes; structure characterization of selected ferrocene complexes with copper, gold and silver by means of ESI/MS.  Proposal of methodology of structure characterization and quantification of the...