The significance of the carbohydrate moieties of the β-adrenergic receptor molecule in the rat brain was examined using the radioligand binding assay method. Thus, this experiment was designed to assess the effects of lectins, concanavlin A (Con A), Phaseolus vulgaris agglutinin (PHA), and wheat germ agglutinin (WGA) on the affinity of the β-adrenoceptor. The rat brain was used and the β-adrenoceptor binding assay was carried out using ³H-dihydroalprenolol as a ligand. Con A and PHA significantly caused an increase in the values of the density of β-adrenoceptor (B_max) and a reduction in the values of the dissociation constant (K_d), but significant changes were not observed with WGA. These results strongly suggest that the carbohydrate moieties of the cell surface containing the β-adrenoceptor molecule may have a crucial role in the drug-receptor interaction, and they imply that the β-adrenoceptor molecule is a glycoprotein which contains N-linked carbohydrate chains.

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We examined the effect of lithium on rat renal handling of p-aminohippurate (PAH) and accumulation of organic ions by rat kidney cortical slices. When infused intravenously with lithium at the rate of 0.13 mmoles/kg/min, decreased renal clearance of PAH as well as no significant changes in glomerular filtration rate and plasma PAH level was observed at the first clearance period during lithium infusion. As we expected, tubular secretion of PAH also was decreased significantly by the infusion of lithium. Therefore, it is suggested that the decrease in the clearance of PAH was due to the decrease in the tubular secretion of PAH. After four days of injections with lithium (4 mmoles/kg, i.p., once a day), a significant decrease in PAH accumulation in the slices was detected. No inhibition of tetraethylammonium accumulation was observed. Lithium pretreatment did not alter water content and extracellular space of the slices. The results suggest that lithium selectively inhibits the organic anion transport system in kidney with the in vivo treatment and follows our previous work in which we showed the in vitro effect of lithium on organic anion accumulation in the slices.

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The present study was undertaken to investigate the roles of sodium ion and the cyclic AMP system in the relaxant effect of papaverine. The effects of papaverine on the ⁴⁵Ca-efflux and the mechanical activity of guinea-pig taenia coli were tested in solutions in which the concentration of sodium ion was varied and compared with those of dibutyryl cyclic AMP. Papaverine dose-dependently caused an acceleration of ⁴⁵Ca-efflux and the synchronous relaxation of a depolarized preparation in normal bathing solution. Dibutyryl cyclic AMP mimicked these effects of papaverine. In Na-free solution, papaverine lost its ability to accelerate the ⁴⁵Ca-efflux, and its relaxant activity was markedly reduced, while dibutyryl cyclic AMP had neither an effect on the ⁴⁵Ca-efflux nor an effect on the muscle relaxation in Na-free solution. Reintroduction of a small amount of sodium ion to the solution, however, recovered these effects of papaverine and dibutyryl cyclic AMP on the ⁴⁵Ca-efflux and the muscle relaxation. These findings indicate that the relaxant effect of papaverine may be in part due to an increase in cyclic AMP-mediated Ca-efflux which requires the presence of external sodium ion. The sodium ion dependence of this Ca-efflux process was also discussed.

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Acquisition processes of discrete lever-press (L-type) and shuttle (S-type) avoidance responses as well as effects of psychoactive drugs thereon were investigated in dd strain mice. The mice showed a more rapid acquisition of S-type avoidance than L-type. However, the mean avoidance rates and occurrences of good-performing mice (showing an avoidance rate of higher than 75%) were almost the same in both types when the training was carried out for more than 15 sessions of 1 hr each. The response rate of L-type avoidance was 2.5-3 times as high as that of S-type avoidance. Methamphetamine and cocaine increased the response rate in almost the same grade in both types of avoidance. Chlorpromazine, haloperidol, pilocarpine and physostigmine suppressed both L-type and S-type avoidance responses. However, the L-type showed a higher sensitivity than the S-type to the avoidance-suppressing effect of these drugs. Atropine, scopolamine and morphine suppressed L-type avoidance response, while they facilitated S-type avoidance. The drug-induced changes in the response rate of the S-type were well correlated with those in the ambulatory activity. The changes in the response rate of the L-type were also consistent with those in the ambulatory activity after administration of methamphetamine, cocaine, chlorpromazine, haloperidol, pilocarpine and physostigmine, but inconsistent after atropine, scopolamine and morphine. The present results suggest that L-type and S-type avoidance responses in mice sometimes show a different change after administration of psychoactive drugs.

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Tritoqualine (TRO), used clinically as an antiallergic drug, did not inhibit histidine decarboxylase activity (HDC, EC. 4.1.1.22.) partially purified from fetal rats and the enzymes prepared from mastocytoma P-815 cells. However, TRQ inhibited the histamine release from rat peritoneal mast cells induced by compound 48/80 and ATP. TRQ was also effective in inhibiting antigen-induced histamine release in rat mast cells sensitized actively or passively by the homologous antiDNP-Ascaris antibody. Preincubation of cultured mastocytoma P-815 cells in a medium including TRQ inhibited non-cytotoxically the histamine release of mastocytoma cells induced by compound 48/80, and the effect of TRQ became more marked with lengthening of the culture period in the presence of TRQ. It was concluded from these results that one of the main actions of TRO as an antiallergic drug was not the inhibitory action on HDC, but might be ascribed to its inhibitory effect on histamine release from mast cells.

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The painting of mouse dorsal skin with 12-O-tetradecanoylphorbol-13-acetate (TPA) (0.2-2.5 nmol/mouse) induced a dose-related increase in vascular permeability, which was determined by pontamine sky blue exudation into the skin 5 hr after the TPA treatment. Marked infiltration of neutrophils in the dermal interstitium was also observed 5 hr after TPA treatment. Treatment of mice with nordihydroguaiaretic acid (NDGA) (10 μmol/mouse), 2, 3, 5-trimethyl-6-(12-hydroxy-5, 10-dodecadiynyl)-1, 4-benzoquinone (AA861) (10 μmol/mouse) and quercetin (3 μmol/mouse) significantly inhibited the TPA-induced dye exudation. However, indomethacin (250-1000 nmol/mouse) tended to inhibit the TPA-induced dye exudation, but the inhibition was not statistically significant. Treatment with AA861 (10 μmol/mouse) also caused a marked inhibition of TPA-induced neutrophil infiltration. Quercetin, NDGA and AA861 inhibited epidermal lipoxygenase activity, but indomethacin failed to inhibit it. On the other hand, indomethacin inhibited epidermal cyclooxygenase, but quercetin, NDGA and AA861 failed to inhibit it. The present study suggests involvement of a lipoxygenase product(s) in the mechanism of the TPA-induced increase in vascular permeability in the dorsal skin of mice.

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The mechanisms of the actions of the β-adrenergic partial agonist (befunolol) were studied in isolated guinea-pig taenia caecum. Befunolol, 2-acetyl-7-(2-hydroxy-3-isopropylaminopropoxy)benzofuran hydrochloride was found to be a typical partial agonist in guinea-pig taenia caecum. The pD₂-value of befunolol was in agreement with its pK_A-value obtained with photoaffinity labeling, but was different from its pA₂-value against isoprenaline and pKi-value obtained from the inhibition of specific[³H]-dihydroalprenolol binding. The Scatchard plot of the specific [³H]-befunolol binding showed two affinity sites of the receptor in the absence of Gpp(NH)p, but the low affinity site was reduced while the high affinity site was not affected in the presence of Gpp(NH)p. The pK_D-value of the high affinity site of befunolol was in agreement with its pA₂-value, and the pK_D-value of the low affinity site was in agreement with its pD₂-value or pK_A-value. These results suggest that the β-adrenergic partial agonist may interact with two different sites: an agonist binding site and an antagonist binding site.

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The role of mast cell degranulation in increased vascular permeability in zymosan-air-pouch inflammation, an experimental model of inflammation induced by zymosan in rats, was investigated. The complement in the inflammatory pouch fluid was exhausted, and mast cells in the pouch wall subcutaneous tissues were degranulated. The histamine level in the pouch fluid was elevated immediately after application of zymosan in the preformed air-pouch and then quickly declined. Plasma exudation into the pouch fluid changed in close parallel with the change of histamine level. Application of compound 48/80 in the air-pouch also brought about liberation of histamine from mast cells, accompanied with elevation of vascular permeability similar to that observed in the zymosan-air-pouch inflammation. However, the amount of the plasma exudation in the zymosan-air-pouch inflammation was about twice as high as that induced by compound 48/80, though the quantity of histamine liberated in the two cases was almost equal. Rats depleted of histamine and serotonin were incapable of responding to compound 48/80, but zymosan still induced increased vascular permeability. A combination treatment with pyrilamine and methysergide did not abolish plasma exudation caused by zymosan, but brought about complete blockade of the vascular permeability response to compound 48/80. These results suggest that some mechanisms independent of degranulation of mast cells are responsible in part for the initial sudden elevation of vascular permeability in zymosan-induced inflammation.

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The role of rat anaphylatoxin in histamine release and increased vascular permeability during the first thirty minute period in zymosan-air-pouch inflammation, an experimental model of inflammation induced by zymosan in an air-pouch prepared on the back of rats, was investigated. Complement depletion by cobra venom factor did not affect the histamine release nor the increased vascular permeability in the inflammation of this type. In spite of apparent anaphylatoxin activity, zymosan activated serum (ZAS) failed to cause any significant release of histamine when infused in the air-pouch on the back. Anaphylatoxin purified from rat serum activated with zymosan in the presence of an inhibitor (ε-aminocaproic acid) of anaphylatoxin inactivator gave a single band in both polyacrylamide gel electrophoresis (PAGE) and SDS-PAGE. The molecular weight estimated by SDS-PAGE was approx. 7, 000. The purified rat anaphylatoxin failed to induce histamine release nor increased vascular permeability even at 50 /μg/ml, although it caused contraction of guinea pig ileum at 0.8 μg/ml. These results suggest that rat anaphylatoxin does not participate in histamine release and increased vascular permeability in the zymosan-air-pouch inflammation.

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Effects of prolonged administration of compound 48/80 (48/80) on the gastric mucosa, serotonin and histamine levels in serum, and mast cells of rats were studied. Daily administration of 48/80 (0.75 mg/kg, i.p.) for 2 or 4 days produced widespread gastric lesions. Further administration of the agent for up to 12 days did not aggravate the lesions which had developed in the early period of administration of the drug. There were only a few visible lesions and numerous healed ones. Almost the same phenomenon was observed with the daily administration of serotonin plus histamine (10 mg/kg each, i.p.) for 2 to 12 days. While 48/80 given for 2 or 4 days increased serotonin and histamine levels in serum, it induced no appreciable increase of these amines after 8 or 12 days of treatment. Serotonin and histamine levels in peritoneal mast cells significantly decreased after the treatment with 48/80, over a 4 day period. The decrease in gastric lesions after prolonged treatment with 48/80 is due to both the depletion of serotonin and histamine from mast cells and an increased resistance of the gastric mucosa with healed lesions.

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The inhibiting influences of some non-steroidal anti-inflammatory drugs (NSAIDs) and other agents on cyclooxygenase (CO) and lipoxygenase (LO) activities in some enzyme preparations were investigated. Washed rat platelets (CO and 12-LO), rat polymorphonuclear leukocytes (PMNs, CO and 5-LO), rat renal medulla homogenate (CO), and purified soybean LO (15-LO) were used as enzyme preparations. The IC50 values of drugs on the enzyme activities were determined in each preparation. In addition, the inhibitory activities of the drugs on the generation of chemiluminescence from PMNs stimulated by phorbol myristate acetate were tested. NSAIDs (indomethacin, ketoprofen and phenylbutazone) showed a selective inhibition of CO in each preparation, but benoxaprofen inhibited both enzymes, especially in PMNs. BW755C, 1 -phenyl-3-pyrazolidone (phenidone), toluene-3, 4-dithiol (dithiol), 6-ethoxy-1, 2-dihydro-2, 2, 4-trimethylquinoline (ethoxyquin) and acetone phenylhydrazone (APH) inhibited both enzyme activities. Nordihydroguaiaretic acid (NDGA) showed a relatively selective inhibition of LO in all the preparations used. APH inhibited soybean 15-LO markedly compared with the other enzymes tested. Ethoxyquin inhibited COs more markedly than LOs, and with regard to LO inhibition, it inhibited 5-LO in PMNs markedly. BW755C, phenidone, ethoxyquin, NDGA, APH and dithiol, which strongly inhibited 5-LO, showed an inhibitory activity on the generation of chemiluminescence from PMNs activated with phorbol ester.

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Intracellular sources of extramitochondrial corticoidogenic cholesterol in bovine, rat and hamster adrenocortical cells were examined in vitro by comparing the species differences in the effects of various inhibitors on the adrenocorticotropic hormone (ACTH)-induced corticoidogenesis. The inhibitors were ML-236B (3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor), W-7 (N-(6-aminohexyl)-5-chloro-1-naphthalene sulfonamide; calmodulin inhibitor), dichlorvos (0, 0-dimethyl-2, 2-dichlorovinyl phosphate; organic phosphorylation inhibitor), chloroquine ((7-chloro-4-4-diethylamino-1-methyl-butylamino) quinoline; lysosomal enzyme inhibitor) and cycloheximide (protein synthesis inhibitor). During 2 to 3 hr incubation periods, the ACTH-induced corticoidogenesis was not inhibited by ML-236B (100 μM) in the bovine and rat adrenocortical cells. In the hamster adrenocortical cells, ML-236B (100 μM) did not affect the ACTH-induced corticoidogenesis during the initial 1 hr incubation periods; but thereafter, the ACTH-induced corticoidogenesis during the subsequent 2 hr incubation periods was completely blocked by ML-236B. The ACTH-induced corticoidogenesis was inhibited by W-7 (up to 25 μM) in the bovine and rat adrenocortical cells, but this was not the case in the hamster cells. Chloroquine (up to 400 μM) inhibited the ACTH-induced corticoidogenesis in the adrenocortical cells of three different species, but the hamster adrenal cells were much more vulnerable than the bovine and rat cells. The ACTH-induced corticoidogenesis in the adrenocortical cells of three different species were equally inhibited by cycloheximide (up to 1 mM). It could be deduced from the present data that intracellular sources of corticoidogenic cholesterol during the ACTH-induced corticoidogenesis in vitro are mainly lysosomes and de novo synthetized cholesterol in the hamster cells, and the main sources are lipid droplets and lysosomes in the rat and bovine cells, respectively.

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Effect of sodium salicylate (SA) and its analogues on lysosomal cysteine proteinases, cathepsins B and H, was investigated. Using a sensitive fluorometric assay, SA was shown to activate cathepsin B but not cathepsin H in the presence of cysteine. Kinetics data showed that the SA-stimulated reaction was due to a 4.5-fold decrease in K_m. SA caused a decrease in the inactivation rate of cathepsin B by leupeptin and E-64. It was suggested that SA stimulates the activation process of the essential cysteine residue.

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We studied the effects of various agents on prednisolone-induced gastric lesions in rats. Gastric lesions were produced by subcutaneous administration of 50 mg/kg of prednisolone once daily for 4 days to non-fasted rats. Daily oral administration of antipeptic, antisecretory agents and 16-dmPGE₂ significantly inhibited the lesions. Antacids and PGI₂ had little or no effect. These results suggest that the concomitant use of the above agents with steroid therapy to provide protection of the gastric mucosa warrants further attention.

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Gastric antral lesions were produced with hemorrhages by vascular ligation-induced ischemia in the prepyloric regions in rats. Additional treatments with intraluminal acid application and indomethacin markedly aggravated the lesions. Histological examination showed that the incidence of ulcers which penetrated the muscularis mucosae was nearly 100% upon treatment with a combination of acid, indomethacin and ischemia. This model provides a useful tool for studying gastric ulcer etiology.

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The effects of an orally active inhibitor of angiotensin-converting enzyme (SA-446) on systemic arterial pressure, renal function and renin release were examined in anesthetized dogs. Intrarenal infusion of the larger dose of SA-446 (0.1 mg/min) caused an increase in RBF, urine flow and renin release and caused a fall in blood pressure. The smaller dose of SA-446 (0.02 mg/min) did not affect the blood pressure, but it increased the urine flow. However, the same dose of SA-446 in combination with probenecid caused a significant fall in blood pressure. The potentiation of SA-446 with probenecid may be explained by the elevation in plasma SA-446 concentration via the inhibition of its tubular secretion by probenecid.

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The ability of methamphetamine to inhibit the firing rate of dopamine cells in the substantia nigra pars compacta (SNC) and the ventral tegmental area (VTA) was studied. Methamphetamine reduced the firing rates of the dopamine cells in a dose-dependent manner in the SNC and the VTA. The doses of methamphetamine required to produce a 50% inhibition of firing rate in the SNC and the VTA were 0.37 mg/kg and 0.28 mg/kg, respectively.

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