The effects of various local anesthetics on rat brain and liver monoamine oxidase (MAO) and their antihemolytic and local anesthetic effects were studied. All local anesthetics tested at 1×10^-7 M to 1×10^-3 M inhibited MAO activity in rat liver mitochondria with 5-hydroxytryptamine (5-HT) as substrate. The order of potency was tetracaine>procaine> dibucaine>lidocaine>prilocaine. Tetracaine and procaine inhibited 5-HT oxidation much more than β-phenylethylamine (PEA) oxidation. Dibucaine inhibited PEA oxidation as much as 5-HT oxidation. Inhibition of MAO by local anesthetics other than dibucaine was reversible. Tetracaine and procaine inhibited 5-HT oxidation competitively, whereas dibucaine inhibited it non-competitively. Antihemolytic effects were observed with dibucaine and tetracaine at concentrations of 6 × 10^-5 M and 1×10^-4 M, respectively. The order of surface anesthetic potencies was dibucaine>tetracaine> prilocaine>lidocaine>procaine. These results suggest that the inhibition of MAO activities by local anesthetics depends on both electrostatic and hydrophobic interactions between these drugs and enzyme-associated phospholipids or the hydrophobic regions of proteins.

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The involvement of α- and β-adrenoceptors in dopamine (DA)-induced positive chronotropic and inotropic effects was investigated in isolated atria from euthyroid and hypothyroid rats. Propranolol at 3×10^-7 M remarkably inhibited the positive chronotropic effect of DA in both euthyroid and hypothyroid rats, and 1×10^-6 M phentolamine inhibited the effects of DA in the presence of propranolol in hypothyroid rats. Propranolol remarkably inhibited the positive inotropic effect of DA in both euthyroid and hypothyroid rats, while phentolamine was effective only in hypothyroid rats. In atria from reserpinized rats, the pD₂-values for DA in both chronotropic and inotropic effects were reduced, but effectiveness of propranolol or phentolamine on DA-induced positive chronotropic and inotropic effects in euthyroid and hypothyroid rats was similar to that in non-reserpinized rats. In hypothyroid rats, DA increased the maximal rate of tension development, which was inhibited by both phentolamine and propranolol. DA shortened the duration of contraction. DA in the presence of phentolamine significantly shortened the duration of contraction but did not in the presence of propranolol. In conclusion the DA-induced positive chronotropic effect is mainly produced by β-adrenoceptor stimulation in both euthyroid and hypothyroid rats, and also by α-adrenoceptors to some extent in hypothyroid rats. The DA-induced positive inotropic effect is produced by α- as well as β-adrenoceptor stimulation in both groups. However, α-adrenoceptors were involved to a greater extent in hypothyroid rats than in euthyroid rats. The stimulation of α-adrenoceptors by DA causes an increase in the maximal rate of tension development without a significant change in the duration of contraction, and the stimulation of β-adrenoceptors by DA causes an increase in the maximal rate of tension development and shortening of the duration of contraction.

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Verapamil was examined for its effect on the frequency of miniature end-date potential (m.e.p.p.) in rat diaphragm muscles. Verapamil (5×10^-5 M) raised the m.e.p.p. frequency. This effect was reversible, reproducible, and concentration dependent. The rise in the frequency was maintained in the presence of external Ca⁺⁺ but was transient in the absence of external Ca⁺⁺. Lowering the temperature to 20°C slightly decreased the average frequency of m.e.p.p. in the normal medium. The effect of verapamil was also present at a low temperature but was delayed in its onset. The resting membrane potential of the muscle fiber was not affected by the agent. These results suggest the possibility that verapamil increases the transmitter release from motor nerve terminals, and the effect is possibly due to a release of Ca⁺⁺ for its initiation, but is dependent on external Ca⁺⁺ for its maintenance.

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We investigate the effects of perfusion with electrolyte solution on secretion of mucus by the frog palatine mucosa. The amount of mucus secreted was determined by measuring the contents of hexosamine in the mucus. Ciliary movement was examined by the particle transport method. The goblet cells, which secrete mucus in the ciliated epithelium, were examined under light and electron microscopes after the perfusion with Ringer's solution. While the mucus secretion was almost completely suppressed by the perfusion with Ringer's solution, the ciliary movement was not suppressed. This suppression was also observed in the presence of bromhexine, pilocarpine or adrenaline, drugs which enhance mucus secretion. Acceleration of ciliary movement as induced by acetylcholine, adrenaline, and serotonin was potentiated by perfusion with Ringer's solution. The mucus secretion was not suppressed by perfusion with a Tris-HCl-substituted Ringer's solution lacking Na⁺ and was partially suppressed when perfused with a Tris-Cl-substituted Ringer's solution free of Ca²⁺. Following perfusion with Ringer's solution, many granules containing mucus were observed in the lower part of a goblet cell in the ciliated epithelium. Moreover, shrinkage of the goblet cell but not the ciliated cell was observed electronmicroscopically. The difference in membrane permeabilities to Na⁺ and Ca²⁺ between the ciliated cell and the goblet cell may play a role in the suppression of mucus by the palatine mucosa.

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Sex difference in the cataleptic response to continuous or intermittent administration of haloperidol (1 mg/kg, i.p.) was examined in the rat. Weekly administration of haloperidol induced a hypersensitivity to haloperidol itself to a greater extent in adult female rats as compared to adult males. Five daily injections of haloperidol induced a marked tolerance to haloperidol in adult female rats but not in males. Ovariectomy in adult rats failed to alter the development of hypersensitivity or tolerance to haloperidol. Orchiectomy in adult rats resulted in the development of a hypersensitivity to haloperidol during the weekly administration and a tolerance during daily injection of haloperidol. In immature female rats, weekly administration begun at 3 weeks of age induced a marked increase in the intensity of haloperidol-induced catalepsy at 7 weeks of age. Daily injection of haloperidol in 3-week-old rats did not show any significant sex difference. These findings suggest that exposure to sex hormones, probably during the time of puberty onset, results in a modification of the activity of dopaminergic and/or related neurons responsible for cataleptic behavior to female and male types. Female sex hormones appear to induce a persistent modification of the dopaminergic system at a certain critical period during the maturation.

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Effects of BCG cells on blood insulin, glucose, glycerol and free fatty acid (FFA), and liver glycogen were examined in rats in vivo. Freund's complete adjuvant (FCA) was used as a solution containing BCG cells. Insulin secretion and lactate production by isoproterenol were enhanced by FCA injection. Hyperglycemia induced by epinephrine was somewhat attenuated by treating rats with FCA. The increment of plasma FFA by isoproterenol was smaller in FCA-injected rats than that in control rats. The amount of glycogen in liver was increased by FCA treatment. Anti-insulin antiserum (AIS) did not modify the lactate producing action of isoproterenol. FFA release stimulated by isoproterenol was enhanced by AIS. Liver glycogen content in FCA-injected rats was decreased by AIS injection. These results suggest that some component(s) of BCG cells may enhance insulin release stimulated by secretagogues, and insulin thus released attenuates some metabolic effects of the agonist.

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The present study was made to investigate the developmental toxicity of ethanol and several sedative-hypnotics (barbital, diazepam, phenobarbital) administered to rat pups via dams for 18 days (day 3-21 after parturition) from the relatively early postnatal stage in terms of changes in the threshold for pentetrazol (PTZ)-induced convulsion, tolerance to, and physical dependence on barbital (B). In the pups of all dosed groups, the convulsive threshold for PTZ is reduced significantly compared with that in the naive group. The sleeping time with B in phenobarbital-exposed offspring was also reduced significantly compared with that in the naive pups. No difference was however, noted in the B concentration of the brain or plasma upon awaking between these groups of pups, which proved that the phenobarbital -exposed pups had obviously acquired a functional tolerance to B. B-dependence formation and the ensuing weight loss and appearance of withdrawal signs, especially clonic-tonic convulsion, were made intense in the phenobarbital -experienced pups. From these results, it may be concluded that exposure to sedative-hypnotics from the early CNS developing stage makes a lowered state of convulsive threshold for PTZ, and therefore, tends to enhance B-withdrawal convulsion. These phenomena were discussed from the viewpoint of monoamine metabolism in the brain.

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Effects of cerebral vasodilators such as bencyclane, cinnarizine, and papaverine were comparatively studied using helically cut basilar and superior mesenteric arteries and radial muscle preparations of pulmonary arteries with the sympathetic nerve isolated from rabbits. The order of relaxation activities on high K⁺-induced contractures was cinnarizine> bencyclane>papaverine in basilar strips and cinnarizine>papaverine> bencyclane in mesenteric strips. Relaxation responses of basilar strips to cinnarizine and bencyclane were faster and more marked than those seen in mesenteric strips. Responses to papaverine were equipotent in both preparations. The action of cinnarizine alone was irreversible. In mesenteric strips, the order of the sensitivity of contractile responses to cumulatively applied biogenic amines was serotonin>noradrenaline>histamine. Cinnarizine produced an antihistaminergic action, while bencyclane produced an antiserotonergic action. In pulmonary arteries, 6×10^-6 g/ml papaverine inhibited contractile responses to 2, 5, and 25 Hz nerve stimulation in a frequency-independent manner together with inhibition of responses to noradrenaline. Bencyclane at 6×10^-6 and 10^-5 g/ml selectively inhibited in a dose-dependent manner contractile responses only to 25 Hz without inhibition of responses to noradrenaline. These results were discussed in comparison with findings of the cerebral vasodilators obtained using other experimental techniques. Spiral strips of basilar arteries from rabbits in combination with peripheral arteries may be used as a simple, quantitative, and reproducible screening method in a preclinical stage for drug evaluation of cerebral vasodilators.

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Antihypertensive effects of a long-term oral regimen of atenolol were studied in SHR, DOCA/saline hypertensive and renal hypertensive rats (one kidney, one clip) in comparison with the effects of propranolol. Both the β-blockers prevented the development of hypertension in SH R but did not affect that in DOCA/saline and renal hypertensive rats. Both of the a-blockers produced no acute hypotensive effects on the established DOCA/saline and renal hypertension of the rat, although they produced a decrease in the heart rate.

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The effects of several amino acids on isolated perfused adrenal glands of dogs were investigated. Methionine (5×10^-5-5×10^-2 M), glutamic acid (5×10^-5-5×10^-2 M), glutamine (10^-4-5×10^-2 M), serine (5×10^-4-5×10^-2 M), cysteine (5×10^-4-5×10^-2 M), arginine (10^-3-5×10^-2 M), and threonine (5×10^-3-5×10^-2 M) consistently increased the rate of release of catecholamine (CA) from the glands for about 8 min. Preinfusion with hexamethonium (C₆, 10^-4 M) plus atropine (5×10^-5 M) reduced the effects of methionine and glutamic acid slightly, and it completely inhibited the effect of acetylcholine (ACh, 10^-6-10^-3 M). Preinfusion of physostigmine did not significantly influence the effects of methionine, glutamic acid, cysteine, and serine. Ca²⁺ free perfusion fluid depressed or abolished the effects of amino acids. They had no effect on the release of CA from isolated chromaffin granules. It seems likely that amino acids depolarize chromaffin cells in the adrenals and release CA from its storage sites. The effects of these amino acids on adrenal medulla cannot involve release of ACh from splanchnic nerve endings.

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Antiulcer effects of geranylgeranylacetone (GGA) on aspirininduced gastric ulcers in rats were studied, comparing them with those of gefarnate. The oral administration of GGA prevented the development of gastric ulcer induced by a single or repeated oral administration (5 consecutive days) of aspirin. The effects of GGA were more potent and more definite than those of gefarnate. The intraduodenal administration of GGA, but not the intragastrical administration, also inhibited the ulceration induced by aspirin in pylorus-ligated rats, while the intraduodenal administration of gefarnate did not. GGA prevented the reduction of the H⁺ concentration and the increment of Na⁺ concentration in the gastric juice induced by aspirin. In addition, the decrease of hexosamine content in the gastric mucosa induced by aspirin was restored to a normal level by GGA, but not by gefarnate. From these results, it was concluded that the protective actions of GGA on aspirin-induced gastric ulcers might be due to its protection from the weakening of gastric mucosal resistances.

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Gastric ulcer induced by the injection of acetic acid (0.025 ml of 20%) into the gastric wall of rats was healed considerably 5 days after the injection of acetic acid. Non-steroidal anti-inflammatory drugs (NSAID) such as aspirin, indomethacin, and phenylbutazone were given consecutively for 5 days, and they exacerbated the ulcer and enlarged the ulcer area. Aspirin caused exacerbation when it was given for the initial 5 days of the ulcer healing process. Phenylbutazone caused exacerbation by the administration for 5 days at the middle stage of the ulcer healing process. In contrast, indomethacin caused exacerbation not only when it was given for the initial 5 days but also when it was given for the middle 5 days. The effect of the antiulcer agent N-acetyl-L-glutamine aluminum complex (KW-110) on the exacerbation was studied. KW-110 at an oral dose of 500 mg/kg inhibited remarkably the exacerbation induced by all of the NSAID used. The development of gastric lesions induced by these NSAID was also prevented by KW-110. Further study was carried out with regard to the influences of KW-110 on the pharmacological properties of NSAID. The results showed no influences of KW-110 on the antiedematous and antipyretic actions of the NSAID.

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The anti-asthmatic activity, pulmonary mechanics and cardiovascular effects of BB-1502 (9-cyclohexyl-2-n-propoxy-9H-adenine) administered by aerosol were evaluated in guinea pigs and dogs and compared with the effects of salbutamol. BB-1502 protected guinea pigs from allergic asthma induced by aerosolized egg albumin antigen. The potency of BB-1502 was approx. 1/7 that of salbutamol when the test drugs and antigen were aerosolized simultaneously, whereas the two drugs were equipotent when administered 60 min prior to the antigen challenge. The duration of the anti-asthmatic action of BB-1502 appeared to be much longer than that of salbutamol. In dogs, BB-1502 and salbutamol showed comparable activity in preventing ascaris antigen-induced asthmatic symptoms. Disodium cromoglycate showed anti-asthmatic activity at high doses while aminophylline was inactive by inhalation. No cardiopulmonary side effects were observed in guinea pigs or dogs following the inhalation of BB-1502. The doses were 800-5, 000 times higher than those needed to produce the anti-asthmatic activity. Salbutamol caused significant tachycardia, hypotension and tachypnea at doses 100-300 times its anti-asthmatic dose.

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Acute ethanol administration (4 g/kg i.p.) induced a significant decrease of nitrosoguanidine-sensitive guanylate cyclase activity in mouse cerebellum. The enzyme activity was maximally attenuated 20 min after the administration and recovered to the initial level within 24 hr. When nitrosoguanidine-sensitive guanylate cyclase activity was assayed in the presence of thiols such as glutathione and dithiothreitol, no significant inhibition of the enzyme activity induced by ethanol was noted. On the other hand, continuous ethanol inhalation for 6 days induced an increase of the nitrosoguanidine-sensitive guanylate cyclase activity in mouse cerebellumn. These results indicate that a single ethanol injection causes a rapid decrease of nitrosoguanidine sensitivity of cerebellar guanylate cyclase.

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Effects of anti-asthmatic drugs on airway resistance and plasma level of cyclic AMP were investigated in guinea pigs sensitized and nonsensitized with egg-albumin. Histamine increased airway resistance in the both groups of guinea pigs, and guinea pigs sensitized with egg-albumin were more sensitive to histamine. Anti-asthmatic drugs inhibited dosedependently the increase of airway resistance caused by histamine. Sensitization with egg-albumin decreased the potencies of the β-adrenoceptor stimulants, salbutamol and isoprenaline, but not that of aminophylline. The plasma level of cyclic AMP was increased by salbutamol and isoprenaline, but not by aminophylline. The increased plasma level of cyclic AMP by β-adrenoceptor stimulants was not attenuated by sensitization with egg-albumin.

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Effects of 3'-Me-DAB on MAO in rat liver mitochondria, in vitro, were investigated. 3'-Me-DAB at a concentration of 1×10^-5 M inhibits MAO activity about 40%, and this inhibition recovered to the control value after dialysis overnight against 0.001 M phosphate buffer. MAO activity was inhibited in an apparently competitive fashion by 3'-Me-DAB. These results indicate that 3'-Me-DAB binds to mitochondrial MAO with a weak affinity in vitro. The K_m value toward benzylamine was 220 μM using both the mitochondria from the liver of rats fed a basal diet and those from rats ingesting 3'-Me-DAB. The activity of these enzyme preparations did not revert after dialysis to the control values of rats fed a basal diet. The titration experiment of MAO by pargyline suggests that the decrease of MAO activity, in vitro, is mainly due to the decrease of active MAO molecules in these mitochondrial preparations from livers of rats ingesting 3'-Me-DAB.

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The hyperuricemic effect of cholinergic agents was studied in rats given potassium oxonate which inhibits urate oxidase and in functionally hepatectomized rats. Acetylcholine slightly increased plasma uric acid in the oxonate-treated animals, and the effect was markedly enhanced by pretreatment with physostigmine. Carbachol alone showed the hyperuricemic effect at a smaller dose than acetylcholine. The hyperuricemic effects of physostigmine plus acetylcholine and carbachol alone were also observed in eviscerated rats with nonfunctioning livers. Nephrectomy markedly potentiated cholinergic agent-induced hyperuricemia, and methylatropine but not hexamethonium apparently abolished the induction of hyperuricemia both in potassium oxonate-treated rats and in eviscerated rats with nonfunctioning livers and without kidneys. However, carbacholinduced hyperuricemia was not found in rats given allopurinol whose plasma levels of uric acid were maintained by exogenously administered uric acid. These results supported the ideas that the hyperuricemic effect of cholinergic agents is due to the stimulated production of uric acid and that uric acid production in tissues other than the liver and the gastrointestinal viscera is closely related to the induction mechanisms of hyperuricemia.

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The contribution of prostacyclin (PGI₂) to the coronary vasodilating action of arachidonic acid (AA) and bradykinin (BK) was examined in isolated perfused guinea-pig hearts. The injection of AA (100 to 1, 000 ng) and BK (1 to 100 ng) into the heart resulted in a dose-dependent increase in the total amount of coronary flow and a release of 6-keto-prostaglandin F_1α, a stable metabolite of PGI₂. Both AA and BK showed weak positive chronotropic effects. In addition, higher doses (300 and 1, 000 ng) of AA caused a transient reduction in the coronary flow rate, left ventricular systolic pressure, and left ventricular dp/dt. The changes in coronary flow, release of PGI₂, and all cardiodynamic parameters induced by AA were abolished by pretreatment of the preparation with diclofenac-Na. On the other hand, the BK-induced increase in coronary flow rate was only partially reduced by diclofenac-Na when the release of 6-keto-prostaglandin F_1α was completely inhibited. It is concluded that in isolated perfused guinea-pig hearts, BK has both PGI₂-independent and PGI₂-dependent coronary vasodilating actions; the latter action is less than 25%, and the coronary vasodilating action of AA is mainly mediated via PGI₂.

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Influences of several α-adrenoceptor antagonists on the triphasic time response curves of phenylephrine, which are characterized by an initial increasing phase followed by a declining phase and then a second increasing phase, were investigated in the guinea-pig left atria pretreated with sotalol (5×10^-5 M) and driven at 0.2 Hz. Phenoxybenzamine (10^-6 M) blocked both the positive and the negative inotropic effects and resulted in disappearance of the characteristic pattern, although lower concentrations (10^-8-10^-7 M) preferentially attenuated the positive phase. Phentolamine (10^-7-6×10^-6 M) and yohimbine (10^-6-10^-5 M) preferentially inhibited the negative phase and potentiated the positive inotropic effect, thus changing the pattern to a biphasic or a monophasic one. Prazosin depressed concentration-dependently the positive inotropic effect and blunted the triphasic pattern (10^-9-10^-8 M) or altered the pattern to a biphasic one (10^-7 M). In the presence of 10^-6 M prazosin, only the negative inotropic effect was observed to subsist. This negative inotropic effect was antagonized by 3×10^-6 M phentolamine. The present results suggest that there may exist two distinct types of postsynaptic α-adrenoceptors in the left atria of guinea pigs, one type mediating the positive inotropic effect and the other type mediating the negative inotropic effect.

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The effect of malotilate (diisopropyl 1, 3-dithiol-2-ylidenemalonate) on the protein synthesis in rat liver was studied in vivo and in vitro. Oral administration of malotilate to rats caused an increase in the protein and RNA contents of the liver and led to an acceleration of ¹⁴C-leucine incorporation into microsomal and cytosol proteins. In a cell-free system, the protein synthesis was enhanced by treatment with malotilate, and an unknown factor(s) which participates in the protein synthesis was found in the cytosol fraction prepared from malotilate treated livers. These results suggest that malotilate is a new type of inducer for protein synthesis. On the basis of the observations obtained in the present study, a hypothesis can be formulated that malotilate enhances liver protein synthesis by accelerating RNA synthesis and/or increasing the transport of RNA from nuclei to cytosol in rat liver.

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