Binding activities of a recombinant human interferon-γ (IFN-γ) preparation with 5 human tumor cell lines, including lung large cell carcinoma PC-13, lung small cell carcinoma QG-90, amelanotic melanoma HMV-1, renal carcinoma ACHN and Burkitt lymphoma Daudi, were compared with those of IFN-α_2a. Three out of five human tumor cell lines, ACHN, HMV-1, and QG-90, were highly susceptible to IFN-γ : the concentrations required to inhibit 50% of the growth of cells (IC₅₀) of ACHN, HMV-1, and QG-90 were 26, 11 and 7 pM, respectively. IFN-α_2a also markedly inhibited the growth of ACHN, HMV-1 and Daudi cells : the values of IC₅₀ for the former and latter cells were 20, 31 and 0.8 pM, respectively. With these susceptible cells, larger amounts of IFN_-γ were bound than with resistant cells. On the other hand, IFN-α_2a bound all cell lines, irrespective of the susceptibilities of cells. The values of the apparent dissociation constant (K_d) of binding of both IFNs ranged from 1.3 to 7.3×10^-10M. The competitive binding test revealed that the binding properties of IFN_-γ were different from those of IFN-α_2a. Under the present experimental condition, it could be said that, with IFN_-γ, the susceptibilities of cells were linked of the expression of the receptors, but there were some exceptions with IFN-α_2a.

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Local induction of a cytotoxic factor (CF), which was reported by us to be a tumor necrosis factor (TNF)-like molecule, in murine tumor tissues by i.v. administration of antitumor polysaccharides was studied. The CF was measured by cytolysis assay against L929 fibroblasts in vitro. The antitumor polysaccharides mannoglucan polyalcohol (MGA), lentinan, carboxymethyl-(1→3)-β-D-linear glucan DP540 (CM-TAK) and yeast mannan induced the CF in MH134 hepatoma tissues inoculated intradermally, with MGA inducing the highest level of the CF. MGA induced the CF in MM46 mammary carcinoma, Ehrlich carcinoma, and MH134 hepatoma, the growth of which were all inhibited by MGA, but not in Lewis lung carcinoma and EL-4 lymphoma, which are therapeutically resistant to MGA. MGA induced the CF in solid MH134 hepatoma tissues inoculated subcutaneously or intramuscularly as well as intradermally, but not in ascitic fluids with intraperitoneal MH134 hepatoma on which MGA is ineffective. These findings suggest that CF induction is correlated with the antitumor activity of polysaccharides. CF induction in tumor tissues was detectable 6 h after i.d. inoculation of MH134 hepatoma. Even in nontumorous inflammatory skin tissues produced by injection of TAK, the CF was induced by MGA. Thus, the early inflammatory reaction with accumulation of host cells and MGA treatment act cooperatively in local induction of the CF.

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Inositol 1, 4, 5-trisphosphate (IP₃) caused a contraction in skinned single smooh muscle cells from the guinea-pig taenia coli. The contractile response to IP₃ was rapid (half time < 5s), concentration-dependent (0.01-10μM, EC₅₀ ; 0.1μM) and also depended on the concentration of Ca²⁺during preloading. IP₃ induced a rapid ⁴⁵Ca²⁺ release from the skinned single cells which were preloaded with 10^-6M Ca²⁺. The contractile response caused by IP₃ was not enhanced by simultaneous application of caffeine (25mM). The inhibitory effect of procaine on IP₃-induced contraction was less than that on caffeine-induced contraction. These results suggest that IP₃ also plays an important role in the contractile response in smooth muscle cells from guinea-pig taenia coli and that the mechanism of Ca²⁺ release from intracellular storage sites by IP₃ is different from that by caffeine.

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The effects of clonidine on a high K⁺-induced release of noradrenaline (NA) were studied in 70-d-and 2-year-old rats. Treatment with 0.1 and 1.0μM clonidine significantly (p < 0.01) inhibited 20mM KCl-evoked L-[³H]NA release from cerebral cortical slices in 70-d-old rats. The amounts of high K⁺-evoked L-[³H]NA release were markedly decreased at 2 years, compared to that at 70 d. In addition, the inhibitory effects of clonidine on high K⁺-evoked L-[³H]NA release were no longer observed in 2-year-old animals. These results suggested that presynaptic functions, including the modulation of NA release by α₂-adrenoceptors, could become low in the brains of the 2-year-old rats.

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The effect of chlorpromazine (0.5 and 4 mg/kg) on plasma catecholamines (adrenaline and noradrenaline) concentrations was investigated in rats. After an i.v. bolus administration of chlorpromazine, plasma adrenaline and noradrenaline concentrations showed a dose dependent increase. In order to clarify the pharmacokinetics of catecholamines in plasma, i.v. infusion of adrenaline or noradrenaline was also carried out. Plasma catecholamines after i.v. infusion showed typical characteristics of a one compartment model with a zero order production rate of endogenous catecholamines. From the data observed, a mathematical model was constructed to elucidate the relationship between the pharmacokinetics (brain concentrations) and the pharmacologic effect (plasma catecholamines concentrations) of chlorpromazine in rats. The results indicated that the time courses of plasma adrenaline and noradrenaline concentrations after an i.v. administration of chlorpromazine were described reasonably well by a simple pharmacokinetic-pharmacodynamic model.

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Kinetics of the pharmacologic effect of chlorpromazine was investigated in intact fed rats. After i.v. bolus administration of chlorpromazine (0.5, 2, 4 mg/kg), the time courses of plasma glucose, insulin, adrenaline and noradrenaline levels as well as serum and brain concentrations of the drug were determined. Since the hyperglycemic effect of chlorpromazine is known to be attributable to the endogenously released catecholamines, the effects of adrenaline and noradrenaline on the plasma glucose and insulin regulation system were also determined. The plasma glucose regulation system in rats was investigated by an i.v. glucose tolerance test. From the date obtained, a pharmacokinetic (PK)-pharmacodynamic (PD) model as well as the plasma glucose regulation model was constructed. The hyperglycemic effects of catecholamines during and after i.v. infusion were reasonably well correlated with the plasma concentrations of catecholamines using the PK-PD model. Since a quantitative relationship between plasma concentrations of catecholamines and the brain concentration of chlorpromazine was established in the previous report, the time course of hyperglycemic effect of chlorpromazine was analyzed. The result indicated that the hyperglycemic effect can be described quantitatively by a simple PK-PD model with plasma glucose regulation system, using brain concentrations of chlorpromazine in rats.

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The characteristics of exsorption and/or excretion of procainamide and its metabolite, N-acetylprocainamide (NAPA), into the small intestinal lumen in both normal rats and rats with acute renal failure (ARF rats) induced by uranyl nitrate were investigated by an in situ single-pass perfusion technique. The exsorption of procainamide and NAPA from blood into the intestinal lumen was increased in ARF rats compared with normal rats. The mean apparent renal, biliary and intestinal clearance values of procainamide were 186, 1.83 and 73.9 ml/h/kg in normal rats, respectively, and were 2.02, 1.37 and 55.8 ml/h/kg in ARF rats respectively. Furthermore, the mean renal, biliary and intestinal clearance values of NAPA were 35.2, 19.4 and 21.1 ml/h/kg in normal rats, respectively, and were 1.12, 21.0 and 26.0 ml/h/kg in ARF rats, respectively. There was little difference in the intestinal clearance values of procainamide and NAPA between normal and ARF rats. The ratio of nonrenal clearance/total body clearance was greater in ARF rats than in normal rats. Treatment with oral activated charcoal reduced the serum NAPA levels in both normal and ARF rats, and had little effect on the serum procainamide levels in normal rats, while it reduced the serum drug levels in ARF rats. Consequently, the increase in both drugs transported into the intestinal lumen induced by renal failure may enhance the intestinal clearance of the drug by oral administration of activated charcoal.

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Antitumor activity of three derivatives of chemically synthesized diacyloxyacylglucosamine-4-phosphate (acyl-GlcN-4P) linked 3-deoxy-D-manno-2-octulosonic acid (KDO) and 12 derivatives of acyl-GlcN-4P or acyloxyacylglucosamine-6-phosphate (acyl-GlcN-6P) with chiral acyloxyacyl groups at the C-2 and C-3 positions was examined. Ehrlich carcinoma cells (1×10⁴) were inoculated i.p. into ddY mice on day 0, and these compounds (100μg/d/mouse) were administered i.p. on days -5, -2, +1, +3, and +5. Although the antitumor activity of the acyl-GlcN-4P linked KDO was weaker than that of the natural lipopolysaccharide, groups of mice administered A-301 with di-3-hexadecanoyloxy-tetradecanoyl [(R)C₁₄-O-C₁₆] at C-2, -3, and A-303 with di-3-tetradecanoyloxytetradecanoyl [(R)C₁₄-O-C₁₄] showed longer mean survival times than the control group. However, KDO-attachment appeared not to enhance the antitumor activity of acyl-GlcN-4P. The group of mice administered acyl-GlcN-4P (A-145) or acyl-GlcN-6P (A-144 and A-146), which have an acyloxyacyl group at C-2, -3, showed prolonged survival times when compared to the control group, but the differences were not significant. On the other hand, when compound A-107 with [(S)C₁₄-O-C₁₄] at the C-2 position and 6-phosphate was administered to 5 mice, 3 mice survived for 25d. Furthermore, mitogenicity for splenocytes of C57BL/6 mice and lethal toxicity in C57BL/6 mice sensitized with D-galactosamine were observed with the acyl-GlcN-4P or-6P derivatives with (R) or (S) isomers of fatty acid. The findings suggest that these activities do not correlate with stereoisomer of fatty acids and the position of phosphate group.

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The inhibitory effects of ozagrel (OZA), an imidazole derivative and a specific thromboxane synthase inhibitor, on a monooxygenase system in mouse hepatic microsomes were studied. Pentobarbital sleeping time was significantly prolonged by i.p. administration of a single dose of 100mg/kg of OZA, and the potency of OZA for the prolongation of sleeping time was similar to that of cimetidine. In vitro, OZA inhibited aminopyrine N-demethylase, aniline hydroxylase and testosterone 6β-and 7α-hydroxylase activities in hepatic microsomes with inhibition constants (K_i) of 0.19-3.72mM. The potency and the mode of inhibition of OZA for these enzyme activities were similar to those of cimetidine, while no inhibitory effect of OZA on testosterone 16α-hydroxylase activity was found. A spectrophotometric study revealed that the imidazole moiety of OZA binds to cytochrome P-450 and has little effect on reduced nicotinamide adenine dinucleotide phosphate cytochrome c reductase activity. These results indicated that OZA is an inhibitor of some cytochrome P-450-mediated drug metabolism in hepatic microsomes.

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