The electrophysiological effects of bunaftine were studied using the glass microelectrode technique. Bunaftine at 1, 5 and 10 mg/l produced a concentration-dependent depression of the maximum rate of rise of the action potential in guinea pig papillary muscle preparations without affecting the resting membrane potential and the action potential amplitude. The action potential duration (APD₅₀, APD₉₀) was significantly prolonged by the treatment with 1 and 5 mg/l bunaftine, while it was not changed by the treatment with 10 mg/l. The absolute refractory period (ARP) was also prolonged dose-dependently by the treatment of bunaftine; It was excessively prolonged (177% of control) at the concentration of 10 mg/l. Disopyramide produced similar electropysiological changes to those of bunaftine except for the prolongation of ARP. ARP/APD₉₀ ratio was significantly increased by bunaftine, but not by disopyramide. These electrophysiological effects of bunaftine and disopyramide observed in guinea pig ventricular preparations were similarly found in canine ventricular muscle preparations. These results indicate that the electrophysiological characteristics of bunaftine are similar to those of disopyramide in that the most prominent effect was the prolongation of ARP.

View full abstract

The effects of TC-80 on acute and chronic pain in rats and mice were examined. Single oral administration of TC-80 at 50 ?? 300 mg/kg was not analgesic in the phenylquinone writhing, acetic acid writhing, and hot plate tests in mice or the tail flick test in rats. Three-weeks administration of TC-80 in a dose of 100 mg/kg/day, p.o., to rats had no analgesic action in the acetic acid writhing and tail flick tests. When TC-80 was given orally in a dose of 100 mg/kg/day for 3 weeks to rats with adjuvant arthritic chronic pain, analgesic effects were observed 2 weeks after the start of administration in males and in ovariectomized estrone-supplemented females; the effect seen in the females was statistically significant. Changes in the bones of the hind paws were examined radiologically, and synovitis, periosteal new bone formation and bone destruction were examined histopathologically in the females. These variables were improved by treatment with TC-80 for 3 weeks. It is concluded that TC-80 has no analgesic effect, but may inhibit chronic pain by anti-osteoporotic action on bone disease.

View full abstract

Electroencephalographic (EEG) effects of 450191-S and its metabolites were investigated in unanesthetized rabbits with chronic electrode implants, and they were compared with those of nitrazepam and estazolam. 450191-S at doses of 0.1 ?? 0.5 mg/kg, i.v., induced a drowsy pattern of spontaneous EEG: high voltage slow waves and spindle bursts increased in the cortex and amygdala, while the hippocampal theta rhythm was desynchronized. In addition, low voltage fast waves appeared particularly in the cortical EEG. The EEG arousal response to auditory stimulation and to electric stimulation of the mesencephalic reticular formation, posterior hypothalamus and centromedian thalamus was markedly suppressed by 450191-S. The photic driving response elicited by a flash light in the visual cortex was significantly suppressed by 450191-S. 450191-S showed no significant effect on the recruiting response. The EEG effects of nitrazepam were qualitatively similar but less potent and shorter in duration of action than those of 450191-S. The effects of estazolam were approximately as potent as those of 450191-S, but its duration of action was much shorter than that of 450191-S. 450191-S was more potent than nitrazepam and approximately equipotent to estazolam in suppressing hippocampal and amygdaloid after-discharges. The EEG effects of M-1 and M-2 were similar to those of 450191-S in both qualitative and quantitative aspects. The effects of M-A were quantitatively similar but less potent and shorter in duration of action than those of 450191-S.

View full abstract

Anti-inflammatory effects of proglumetacin maleate (PGM), a new indomethacin (IND) derivative, were compared with those of IND on an equimolar-dose basis. PGM produced a dose-dependent inhibition of vascular permeability and carrageenin edema. These inhibitory effects of PGM were greater when given 4 hr prior to phlogistic agents than when given 1 hr before. Moreover, these effects of PGM were long-acting. Inhibitory effects of PGM on kaolin edema and UV-erythema were slightly less active than those of IND. PGM markedly reduced the leukocyte migration in carrageenin pleurisy. Subacute anti-exudative and anti-granuloma effects of PGM were nearly equal to those of IND. Also, PGM showed strong prophylactic and therapeutic effects on adjuvant arthritis, the model of chronic (immuno-reactive) inflammation. These effects of PGM were superior or equal to those of IND. These pharmacological properties of PGM suggested its potential usefulness in rheumatic and other inflammatory disorders. It was considered that the mode of action of PGM mainly depended on its active metabolite, IND. However, PGM was also active in the case of local administration into the sites of inflammation on rat hind paw edema. Therefore, it seemed that PGM had a different behavior than a so called “ prodrug ”.

View full abstract

The ameliorating effects of an enteral nutrient for liver failure (SF-1008C), which is enriched with branched-chain amino acids (BCAA) and includes few aromatic amino acids (AAA), were investigated. The blood ammonia, plasma and brain free amino acids, intracerebral amine concentrations and electroencephalogram were measured in portacaval shunted rats with 10% ammonium acetate (3 ml/kg, i.p.) (PCS) as a model of hepatic encephalopathy. The blood ammonia and plasma free amino acid concentrations in PCS rats were significantly increased in comparison to sham-operated (Sham) rats. Thus, the plasma BCAA/AAA ratio in PCS rats was appreciably reduced. Concomitant with the abnormal plasma amino acid concentrations, the brain free amino acid concentrations in PCS rats were markedly increased in comparison to the Sham rats. Moreover, the intracerebral tryptophan (Trp) and 5-hydroxyindol acetic acid (5-HIAA) concentrations were significantly increased, and the intracerebral dopamine (DA) concentration was significantly decreased in the PCS rats. The intracerebral serotonin (5-HT) and norepinephrine (NE) concentrations were, however, hardly changed. A smaller voltage for the electroencephalogram was used in the PCS rats than in the Sham rats. Abnormal plasma and brain free amino acid concentrations in PCS rats were normalized by oral administration of SF-1008C, and the low voltage electroencephalograms in the PCS rats were suppressed. On the other hand, abnormal plasma and brain free amino acid concentrations in the PCS rats were hardly normalized by oral administration of ED-AC, an elemental diet based on an amino acid composition of egg protein. These results suggest that SF-1008C affects brain free amino acids, intracerebral amine concentrations and electroencephalogram by ameliorating abnormal plasma free amino acid concentrations. Moreover, there is a highly significant correlation between the plasma BCAA/AAA ratio and the brain BCAA/AAA ratio, and this finding suggests that the plasma free amino acid patterns reflect the brain free amino acid patterns.

View full abstract

The mechanism of action of secretagogic expectorants (ex., ambroxol) has not been clarified. Recently, attention has been directed to the relationship of their action to pulmonary surfactants. In the present study, the fatty acid (FA) composition of phosphatidylcholine (PC), which is the main physiological surfactant, was investigated using sputum, respiratory tract fluid, mucin-like substance, lung washings and lung tissue of rabbits. Effects of ambroxol (20 mg/kg, i.s.) on several parameters such as output volume, FA contents of PC, protein content and viscosity of respiratory tract fluid of rabbits were also investigated. In respiratory tract fluid, lung washings and mucin-like substance of rabbits, saturated FA, especially C16 : 0, were predominant components of PC; while in sputum and lung tissue of rabbits and respiratory tract fluid of hens, unsaturated FA, especially C18 : 1 and C18 :2, were more predominant components in comparison with those in the above specimens. Ambroxol significantly increased the contents of C16 : 0, saturated FA and total FA of PC, and it also increased protein content with an increase in the viscosity of respiratory tract fluid. These results suggest that in the respiratory tract fluid of rabbits, PCs are pulmonary surfactants, and the increasing secretion of pulmonary surfactant is likely to be involved in the expectorant action of ambroxol.

View full abstract