A smooth muscle relaxant, Aspaminol (1, 1-diphenyl-3-piperidinobutanol hydrochloride) relaxed a KCl-depolarized rat uterus and shifted a dose response curve of CaCl₂ towards higher doses. Aspaminol, a tertiary amine, may penetrate into the KCl-depolarized muscle cells. In order to study mechanisms for relaxation of the KCl-depolarized rat uterus by Aspaminol, effects of Aspaminol on Ca-uptake by mitochondrial and microsomal fractions from the rat uterus were studied. Aspaminol inhibited Ca-uptake by both fractions. Inhibition of Ca-uptake by the mitochondrial fraction seems to increase intracellular Ca²⁺. Therefore, inhibition of Ca-uptake by the mitochondrial fraction is considered to be not associated with relaxation of uterus induced by Aspaminol. Since the microsomal fraction is known to form microsacs, the microsomal fraction was used as smooth muscle models. Inhibitory effect of Aspaminol on Ca-uptake by the microsomal fraction suggest a decrease in the intracellular concentration of Ca²⁺ of the uterine smooth muscle relaxed under the influence of Aspaminol.

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The effects of intrahippocampally administered catechol-and indoleamines on the two types of hippocampal seizure discharges elicited by electrical and chemical stimulation were examined in unanesthetized rabbits. The catecholamines norepinephrine (NE) and dopamine (DA), injected into the hippocampus in doses of 100-200μg, inhibited electrically induced hippocampal seizure discharges with a 50% increase in the stimulation threshold. However 5-hydroxytryptamine (5-HT) at doses of 50 μg to 100 μg caused no effect on electrically induced seizure discharges. On the contrary, 5-HT and 5-hydroxytryptophan (5-HTP) at a dose of 50 μg potentiated carbachol (5 μg)-induced hippocampal seizure discharges, prolonging the duration of seizure discharge three times the control. NE and DA had no effect on this chemically induced hippocampal discharges. It is therefore suggested that the effects of monoamines on hippocampal seizure discharges are very much dependent on the type of stimulation employed for the induction of this phenomenon.

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In the presence, but not in the absence of Cu²⁺, ascorbate decomposes histamine in citrate phosphate buffer (pH 6.5) at 37°, but not at 0°. The breakdown is completely inhibited by catalase, but only slightly by superoxide dismutase, and scavengers of OH·like benzoic acid, ethanol or potassium iodide. A¹O₂ scavenger, α-tocopherol also did not show significant effects on the reaction. On the other hand, addition of H₂O₂ to the reaction mixture markedly enhances the rate of histamine breakdown induced by ascorbate or ascorbate-Cu²⁺ systems. However, H₂O₂ alone cannot breakdown histamine even in the presence of Cu²⁺. Histamine breakdown induced by ascorbate appears to be dependent upon the autooxidation of this vitamine. From these results and the findings reported by Chatterjee et al. that the products of its aerobic oxidation, dehydroascorbic acid and H₂O₂ were ineffective in reacting with histamine in the presence of Cu²⁺, it is concluded that the combination of H₂O₂ and the intermediate of ascorbate oxidation (monodehydroascorbic acid or other unstable species), both of which are produced during the autooxidation of ascorbate, plays a major role in the histamine transformation by ascorbate-Cu²⁺ system.

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Acrosin was extracted from boar sperm and purified by Sephadex gel filtration and affinity chromatography on Phe-Phe-Arg Sepharose 4B in acidic condition. Its enzymic properties were characterized in comparison with trypsin. The oligopeptides with Arg at the carboxy-termini were used as the ligands for affinity chromatography. Phe-Phe-Arg adsorbed acrosin at pH 5 and released it at pH 3. To adsorb acrosin, it was found that the ligand should be longer than tripeptide with Arg in the carboxy-termini. Disc gel electrophoretogram of purified boar acrosin gave a broad band consisted from three fractions which hydrolysed N-α-benzoyl-arginine ethylester (BAEE). The pH optimum and inhibition spectra were similar to those of trypsin, however, the influence of urea on them were very different among each other. Calcium ion decreased K_m for BAEE, and increased K_i of aprotinin. The kinetic analysis of acrosin for its substrate and products resulted that K_m for BAEE was minimal at around pH 8 and maximal at pH 5, on the contrary, K_i of the product was low at pH 5, but progressively increased along the elevation of pH. The same tendency was observed for trypsin. From the attitudes on the affinity chromatographies and the pH profiles of kinetic parameters, it was concluded that the active sites of acrosin and trypsin were similar to each other.

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After the administration of aminopyrine with or without barbital to rats, aminopyrine and its main metabolites were detected in plasma and the brain by means of gas chromatography-mass spectrometry. It was clarified that a marked increase of 4-monomethylaminoantipyrine was observed in the case of coadministration of aminopyrine and barbital, while the plasma level of aminopyrine decreased significantly compared with single administration.

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Effect of taurine on drug absorption from the rat gastrointestinal tract was investigated by using in situ loop method for the stomach and in situ recirculation method for the small or large intestine. Aspirin absorption from the stomach or the small intestine was enhanced by the presence of taurine, but not from the large intestine. The absorption enhancement effect of taurine was not only site-specific, but also substrate-specific. Taurine increased the absorption of aminopyrine from the small intestine, but not from the stomach. On the other hand, the absorption of salicylamide, o-methoxybenzoic acid and o-ethoxybenzoic acid was enhanced in the stomach, although they were not influenced in the small intestine. Furthermore, among the taurine analogues investigated only homotaurine showed the taurine-like action in the small intestine. Glycine also increased the gastric absorption of aspirin. These effects were observed neither by the pretreatment of the intestine with taurine, nor by i.v. administered taurine. Taurine at the site of drug absorption, even at a low concentration, seems to influence the drug absorption due to its effect on the permeability characteristics of the mucosal membrane.

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Actions of quisqualic acid on the crayfish neuromuscular junction were examined and compared with those of glutamate. The glutamate and quisqualate currents were induced in the voltage-clamped muscle. When their peak amplitudes were plotted against the current intensity of iontophoretically applied drugs, the hyperbola resulted. The amplitude of the maximum response to quisqualate was similar to that to glutamate. When the amount of quisqualate which was simultaneously applied with glutamate was changed, the amplitudes of the maximum response of glutamate plus quisqualate did not vary much at the top of the doseresponse curves. Bath application of quisqualate in concentrations above 10^-6 M produced a large depolarization of the muscle fiber, but this response was maintained after it reached a maximum, unlike glutamate. On the other hand, the amplitude of excitatory junctional potentials (EJPs) was gradually decreased. A quantum analysis of the extracellular EJP demonstrated that this decrease in EJP amplitude produced by quisqualic acid was due to the postsynaptic event. This decrease in EJP amplitude could not be prevented by exposure of the muscle fiber to concanavalin A, which completely blocked development of desensitization of the glutamate receptor. Based on these results, it is doubtful that the decrease in EJP amplitude produced by quisqualic acid is due to desensitization of the neuroreceptor.

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The binding of methylene blue (MB) and chlordiazepoxide (CDP) to rabbit plasma was determined by ultrafiltration. The fractions (f) unbound of these two drugs to the plasma were about 23-29 and 6-12%, respectively. These fvalues were comparable to binding data of these two drugs to bovine serum albumin. The results supported the previous suggestion stating that protein binding would partly account for relatively high value of apparent volume of distribution (V_d') for MB. Therefore, in order to investigate the distributive profile for MB as compared with that for CDP, pharmacokinetic parameters for MB and CDP were estimated from plasma concentration-time data following simultaneous intravenous administration by a bolus injection and by a constant rate infusion in rabbits. The V_d' for MB was found to be dependent of dose in contrast with that for CDP by the infusion experiments at three different doses. These evidences assume that MB would be bound to and/or adsorbed on some biological components other than plasma protein.

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Antitumor activity and toxicity to host of newly synthesized disulfide derivatives of 6-mercaptopurine (6-MP) and 6-thioguanine (6-TG) were examined in murine ascites sarcoma-180 system (total packed cell volume method) by parenteral administration. The compounds tested were 6-alkyl disulfides (carbon number of alkyl group : 2, 3, 4, 5, 6, 7, 8, 10, and 14), 6-branched-alkyl disulfides (iso-propyl, sec-butyl, and tert-butyl), and 6-aralkyl disulfide (naphthyryl). Most disulfide derivatives of 6-MP and 6-TG showed higher antitumor activity (lower ED₅₀) and higher toxicity to host (lower LD₅₀) than parent compounds, but ratios of increase in activity and toxicity were different with each other. The compounds with higher chemotherapeutic index (LD₅₀/ED₅₀) than parent compounds were α-naphthyryl (8.7) disulfide in a series of 6-MP (7.5) derivatives ; and sec-butyl (27), tert-butyl (24), octyl (23), decyl (26), and α-naphthyryl (28) disulfides in a series of 6-TG (14) derivatives These 6-TG derivatives were promising for antitumor agents.

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Binding of 2-(4'-hydroxyphenylazo) benzoic acid (HABA) to bovine serum albumin (BSA) was studied by equilibrium dialysis, by the spectrophotometric method and by the absorption spectra of bound HABA. Comparison of equilibrium dialysis with the spectrophotometric method clarified the presence of a undisclosed class of binding sites, which do not cause the spectral change at about 480 nm to HABA, on BSA. Two bands observed on the absorption spectra of bound HABA were attributed to differently perturbed two HABA molecules by BSA, the azo and hydrazone forms, and these two forms correspond to HABA molecules bound to non-metachromasy sites and metachromasy sites, respectively. The concentration of each form was calculated by using estimated molar extinction coefficient.

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Effects of chlorinated benzenes on the activities of δ-aminolevulinic acid (δ-ALA) synthetase and heme oxygenase, the rate-limiting enzyme in heme biosynthesis and degradation respectively, and on the incorporation of ³H-δ-ALA into hemoprotein in the liver of male rats were investigated. Monochlorobenzene (MCB) and 1, 2, 4-trichlorobenzene (TRCB) stimulated significantly the activities of above both hepatic enzymes. After a single injection of 200 mg/kg, heme oxygenase activity was enhanced rapidly and sustained markedly for at least 48 hr by MCB treatment, while that was also enhanced but restored nearly to control levels at 48 hr by TRCB. δ-ALA synthetase activity was once decreased at 6 hr and restored within 12 hr and then reached peak levels (about 2-3 times to control levels) at 24 hr by MCB or TRCB treatment. However, this activity was sustained for 48 hr by TRCB treatment, whereas returned again to nearly control levels by MCB at 48 hr. Cytochrome P-450 content at 48 hr was significantly decreased by MCB (63% to control), in contrast, increased by TRCB (200% to control). When MCB or TRCB injected once daily throughout the study, biphasic disappearance of radioactivity incorporated into CO-binding particles was shown in control and MCB-or TRCB-treated rats. The half-life of the fast phase was about 8 hr in control and about 6 or 13 hr in MCB-or TRCB-treated rats respectively.

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We have prepared anti-carbamazepine antiserum and developed a competitive nephelometric immunoassay for the determination of carbamazepine and its epoxide metabolite in patient blood plasma. The antiserum was raised by immunization of a rabbit with a carbamazepine-(bovine serum albumin) conjugate. A carbamazepine-(human serum albumin) conjugate was used as an assay reagent. Carbamazepine and its epoxide inhibited competitively and almost equally the immunoprecipitation of the carbamazepine-(human serum albumin) conjugate. Therefore carbamazepine and its epoxide could be determined by the measurement of the scattered light from the immunoprecipitate in assay solution on a laser nephelometer. Patient plasma specimens were analyzed, and the values correlated well to those determined by the high-performance liquid chromatography. The epoxide concentrations were considerably lower than therapeutic carbamazepine concentrations, which was certified by the chromatographic results. This immunoassay was rapid (incubation time : within 20 min), simple and precise (coefficient of variation : less than 6%), and required as little as 6 μl of plasma, and seemed suitable for routine monitoring of carbamazepine.

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