Involvement of endothelins in immediate and late asthmatic responses of guinea pigs.

To explore the pathophysiological roles of endothelin isopeptides and receptor subtypes in asthmatic responses, a guinea pig model for asthma was used to test the effects of antiendothelin (ET) serum and selective ET receptor antagonists for antigen-induced specific airway conductance changes as measured by whole-body plethysmography. In this model, all of the animals so far tested demonstrated both the immediate and late asthmatic responses. Although preimmune serum had no apparent effects, anti-ET antiserum suppressed the maximal reduction of specific airway conductance in both the immediate and late asthmatic responses, which suggested that ET(s) are involved in the pathophysiology of both the immediate and late asthmatic responses. The ETB selective antagonists, BQ788 and RES701-1, blocked the immediate asthmatic response but not the late asthmatic response, whereas the ETA antagonists, BQ123 and (Shionogi) 97-139, suppressed only the late asthmatic response without influencing the immediate asthmatic response. In vitro constrictive responses of isolated tracheas and bronchi to ET1 were inhibited mainly by BQ123 and BQ788, respectively, which suggested that distribution of ETA and ETB receptors for bronchoconstriction are topographically distinct along airways. Furthermore, thromboxane A2 and platelet activating factor (PAF) antagonists were effective in suppressing the late asthmatic response but not the immediate asthmatic response. Taken together, our present observations suggest that ET(s) influences pulmonary functions by constricting airway smooth muscle via ETB receptors during the immediate asthmatic response and by modulating pulmonary inflammation via ETA receptors during the late asthmatic response, respectively.

Synthesis of the N-oxides of phenothiazine antipsychotic agents.

Chlorpromazine N-oxide, fluphenazine N4'-oxide, prochlorperazine N4'-oxide, sulforidazine N-oxide, and trifluoperazine N4'-oxide were synthesized by oxidation of the designated nitrogen atom in the N-10 side chain of the respective parent drug with 3-chloroperoxybenzoic acid. In the case of trifluoperazine, a stepwise increase in the amount of oxidant yielded the N1',N4'-dioxide and N1',N4',S-trioxide. The N',S-dioxides of chlorpromazine and sulforidazine were obtained by hydrogen peroxide oxidation of the appropriate parent drug.

Radioimmunoassay for fluphenazine sulfoxide in human plasma.

Antisera to fluphenazine sulfoxide were raised in New Zealand white rabbits to an immunogen synthesized by covalent linkage of bovine serum albumin to 10-[[3-[4-(4-carboxybutyl)-1-piperazinyl] propyl]]-2-trifluoromethyl-10H-phenothiazine 5-sulfoxide. With use of an antiserum, a radioimmunoassay for fluphenazine sulfoxide was developed that is able to quantitate 0.156 ng ml-1 using only a 200 microliter plasma sample with a coefficient of variation less than 5%. The antiserum had negligible cross-reactivities to fluphenazine (less than 1%) and its important metabolites, such as fluphenazine N4'-oxide (1%), 7-hydroxyfluphenazine (less than 1%), and N4'-deshydroxy-ethylfluphenazine (1%). The cross-reactivities with structurally similar phenothiazine 5-sulfoxides, such as those of trifluoperazine, prochlorperazine, perphenazine, and N4'-deshydroxyethylfluphenazine, were considerable, such that the antiserum can be used to develop a quantitative radioimmunoassay for any of these compounds. The reported radioimmunoassay was found to be suitable and adequate to quantitate fluphenazine sulfoxide in the plasma of patients treated with oral or intramuscular fluphenazine.

Synthesis and properties of haptens for the development of radioimmunoassays for thioridazine, mesoridazine, and sulforidazine.

For the separate development of radioimmunoassay procedures for thioridazine and its two major active metabolites, mesoridazine and sulforidazine, three haptens, respectively, 2-methylthio-, 2-methylsulfinyl-, and 2-methylsulfonyl-substituted 10-[2-[1-(2-carboxyethyl)-2-piperidinyl]ethyl]-10H-phenothiazine, were synthesized and characterized. Thioridazine hapten was coupled to bovine serum albumin, whereas the haptens for mesoridazine and sulforidazine were coupled to porcine thyroglobulin. The number of hapten residues per mole of carrier protein was determined in each case by an ultraviolet spectrophotometric method. Polyclonal antibodies to each hapten-protein conjugate were obtained in rabbits, and titers of the antisera were checked by evaluating their binding characteristics to the appropriate tritiated analyte. A hapten for the ring sulfoxide metabolite of thioridazine was also synthesized.

Anticonvulsant evaluation of some 3-oxo and 3-thiosemicarbazono analogues of 1-aryl-1-ethylthio-nonanes and related compounds.

A number of 3-oxo and 3-thiosemicarbazono analogues of 1-aryl-1-ethylthio-nonanes and related compounds were synthesized. Solutions of the thiosemicarbazones in deuterochloroform were shown by PMR spectroscopy to exist principally in the anti configuration at equilibria except when an ortho-methoxy group was present in the aryl ring. In this case intramolecular hydrogen bonding probably accounts principally for the presence of equal amounts of anti and syn isomers. Evaluation of these compounds for anti-convulsant properties revealed that 1-(2-aminoethylthio)-1-(2-chlorophenyl)nonan-3-one hydrochloride (6a) and sodium 2-(N-acetylamino)-3-[1-(2-chlorophenyl)-3-oxononylthio]propionate (6c) were active and thus they could serve as prototype molecules for future development.