The metabolites were identified by gas chromatography-mass spectrometry (GC-MS). When an equimolar mixture of roxatidine acetate hydrochloride and its deuterated compound, labeled with ten deuterium atoms in the piperidine ring, was incubated with the 9000×g supernatant (S-9) fraction of either rat or dog liver homogenate, the oxygenated metabolites of the piperidine ring such as the 3-hydroxypiperidine derivative (M1) and the 2-oxopiperidine derivative (M2) were isolated from rats but M2 was not isolated from dogs. These results suggested that the species differences in the metabolism of the piperidine ring in vitro are similar to that in vivo. The deuterium isotope effect (H/D) was 1.34 for M1 and 1.47 for M2 in rats, while the value for M1 in dogs was 1.69. On the other hand, the formation of these oxidative metabolites was inhibited by carbon monoxide in incubations using hepatic microsomes, suggesting that the reaction was catalyzed by cytochromes P-450.

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The effect of oleic acid-HCO60 mixed micelles (MM) on the absorption of colloidal particles by the large intestine was investigated using the in situ closed loops of rats. Two species of colloidal particles with different sizes, colloidal inks (Platinum ink 2.4-10 nm, Rotring ink 100-800 nm) and colloidal gold particles (mean particle size 5, 20, 40 nm) were chosen. Macroscopic observation showed that in the case of Platinum ink the staining of the mucus of the whole large intestine was promoted by MM and the staining of the rectum remained even after removing the mucus layer. The regional lymph nodes and the thoracic lymph was also stained. On the other hand, in the case of Rotring ink, the stain in the large intestine after removing the mucus layer, in lymph nodes and in the thoracic duct lymph was not observed. The results of quantitative experiments using colloidal gold particles indicated : 1) the upper size limit of colloidal particles absorbed by the large intestine, under the influence of MM was approximately 40 nm, 2) colloidal gold particles were transported from the intestine selectively into the lymphatics and accumulated in the regional lymph nodes, 3) the absorption of colloidal gold particles was largely promoted by MM in the rectum area.

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The effect of oral administration of activated charcoal on serum elimination of ¹⁴C-M79175 injected intravenously in rats was studied. In situ single-pass perfusion studies showed that M79175 and/or its metabolites was transported into the small intestinal lumen. Total radioactivity expressed as equivalents of M79175 exsorbed in the perfusate and excreted in the bile juice was 3.2% and 2.0%, respectively, of dose. Oral administration of multiple doses of activated charcoal significantly decreased the serum concentration and serum half-life of ¹⁴C-M79175. The fecal excretion of ¹⁴C-M79175 after treatment with activated charcoal was increased when compared to that in the control. On the other hand, urinary excretion of ¹⁴C-M79175 after treatment with activated charcoal was decreased. However, there was no significant difference in the cumulative amounts of total excretion (fecal plus urinary excretion) between rats with activated charcoal treatment and rats without charcoal treatment. These results suggest that intestinal dialysis by oral activated charcoal is a reasonable method to enhance the elimination of M79175 from the serum in case of overdose of the drug.

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Treatment of rat reticulocytes with isoproterenol caused about 50, 25, and 25% decreases in β-adrenergic agonist-, fluoride-, and guanine nucleotide-stimulated adenylate cyclase activities, respectively. The desensitization was also induced by dibutyryl adenosine 3', 5'-cyclic monophosphate (cyclic AMP) and 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7) prevented the isoproterenol-induced desensitization, suggesting the involvement of cyclic AMP in the desensitization. Time course studies revealed that the desensitization to NaF-AlCl₃ occurred faster than that to isoproterenol. Furthermore, the rate of the resensitization to NaF-AlCl₃ by removal of isoproterenol was also faster than that to isoproterenol. Thus, it is likely that both guanine nucleotide-binding stimulatory regulatory protein, N_s, and β-adrenergic receptor are sequentially involved in both desensitization and resensitization of the adenylate cyclase system in rat reticulocytes to isoproterenol.

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The relative in vitro antioxidant efficacy of tranilast, a new orally active antiallergic agent, was examined by studying its effects on the generation of reactive oxygen species (ROS) using zymosan-stimulated polymorphonuclear leukocytes and the cell-free, xanthine-xanthine oxidase system. The species investigated were superoxide radical anion (O₂-), hydrogen peroxide (H₂O₂) and hydroxyl radical (OH^*). At concentrations comparable to therapeutic blood levels, tranilast reduced both H₂O₂ and OH^* levels. The inhibitory effect of tranilast was dose-dependent and all ROS levels examined were significantly decreased at the concentration of 100 μg/ml. This antioxidant effect of tranilast appeared to stem from its capability to scavenge ROS because the suppression of ROS was observed in both ROS generation systems at higher concentrations, even though the possibility existed that tranilast directly inhibited nicotineamide adenine dinucleotide phosphate oxidase and/or xanthine oxidase activity. This unique anti-inflammatory pharmacological activity of tranilast suggests its potential clinical application for allergic diseases complicated with inflammation.

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The antitumor activity of 5'-deoxy-5-fluorouridine (5'-DFUR) against Lewis lung carcinoma was examined by implanting the tumor subcutaneously into young (8-11 weeks) and old (24-41 weeks) hybrid (C57BL/6×DBA/2) F₁ (BDF₁) male mice. Oral administration of 5'-DFUR induced a small (7 of 100) but significant (p<0.05) number of 70-d survivors in young mice. However, the antitumor activity was further enhanced in the old mice, and 15 of 46 (32.6%) and 11 of 62 (17.7%) mice survived for 70-d by treatment with 2000 and 1000 mg 5'-DFUR/kg/d, respectively, given on days 1, 5, and 9. The reason for the higher cure rate in old mice was partly analyzed. Toxicity of 5'-DFUR in young and old mice did not differ significantly, regardless of the presence (except 2000 mg/kg) or absence of Lewis lung carcinoma. No survivors were observed after treatment with 5'-DFUR when the tumors were implanted into the aged (15-38 weeks) syngeneic hosts, C57BL/6 mice. On the other hand, the survival time of BDF₁ mice implanted with a constant number of the tumor cells increased significantly with the increase in host age and reached a maximum at the age of 24 weeks. These findings suggest that an optimal activation of 5'-DFUR (to 5-FU) was carried out in the old BDF₁ mice bearing Lewis lung carcinoma and/or that a host-mediated antitumor mechanism of BDF₁ mice, which is reinforced with aging, might participate in the enhancement of the antitumor activity of 5'-DFUR against this tumor.

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The effects of insulin and glucocorticoid on granuloma formation and angiogenesis were studied using an adjuvant pouch in mice and a carrageenin pouch in rats. Carrageenin-induced granuloma formation was suppressed in the diabetic state induced by alloxan in rats. The suppression was restored by adrenalectomy. Corticosterone counteracted the restoration, whereas epinephrine did not, suggesting that the effects of adrenalectomy are due to the lack of adrenocortical hormones rather than epinephrine. The blood corticosterone levels in alloxan mice increased, following the increase of glucose level, to more than 20 μg/dl after 4 weeks. The increase of corticosterone levels disappeared after adrenalectomy. In the mouse adjuvant pouch, corticosterone dose-dependently decreased granuloma formation and angiogenesis. The values of these two parameters obtained with a dose of 20 μg/ pouch corticosterone agreed with those of the serum levels in diabetic mice. Insulin dose-dependently reversed the suppressed angiogenesis of 20 μg corticosterone-treated mice and the dose-response curve approximated the curve of alloxan-treated mice. The effects of diabetes were concluded to involve insulin deficiency as well as glucocorticoid enhancement and the counteraction between the two may control granuloma formation and angiogenesis.

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Highly purified human recombinant interferon-γ (ReIFN-γ) was radioiodinated with ¹²⁵I-Bolton-Hunter reagent and used to characterize the receptor for ReIFN-γ. ¹²⁵I ReIFN-γ specifically and saturably bound four human cells tested, FL, WISH, Daudi, and HL-60, which were reported to have ReIFN-γ binding sites. Scatchard analysis of the binding data of FL cells revealed the presence of 5200 binding sites per cell and a K_d value of 2.1×10^-10M. Although the binding of ¹²⁵I ReIFN-γ was inhibited by unlabelled natural IFN-γ and ReIFN-γ, it was not inhibited by unlabelled human ReIFN-α and ReIFN-β, suggesting that receptors for (Re) IFN-γ were different from those for IFN-α or IFN-β. However, ReIFN-γ displaced the binding of ¹²⁵I ReIFNγ 3 to 5 times more effectively than IFN-γ. Internalization of ¹²⁵I ReIFN-γ bound to the cell surface receptor was observed at 37°C. Pretreatment of FL cells with unlabeled ReIFN-γ caused a concentration-dependent down-regulation in the ReIFN-γ receptor, which was specific for IFN-γ and reversible. From these studies, we concluded that although the ReIFN-γ is not identical to putative IFN-γ, the recombinant form binds to the same binding sites for IFN-γ and does not bind to the binding sites for IFN-α or β.

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Apparent blood flow rate in jejunum, kidney, liver or skeletal muscle was directly measured by the hydrogen gas clearance method in 7-week-old rats anesthetized with urethane at four dose levels (0.5, 0.8, 1.0 and 1.5 g/kg, i.p.). The apparent blood flow in each organ or tissue was reduced with the urethane dose. Jejunal blood flow was most sensitive to the dose-related decrease. Assuming that the organ (or tissue) to blood partition coefficient of hydrogen gas is unity and extrapolating the flow data to zero urethane dose for each organ, the flow rate values were almost comparable with the literature data in conscious rats. The applicability of the hydrogen gas clearance method to examine the effect of age on organ or tissue blood flow in rats was also discussed. Organs with relatively high sensitivity to aging were the stomach, jejunum and kidney.

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The acetohexamide reducing activity in hepatic 10000×g supernatant was significantly higher in male than in female rats. Evidence obtained in this study suggests that the microsomal carbonyl reductase may contribute to the sex difference in the reductive metabolism of acetohexamide in rats.

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