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Biomedical subjects

Y Iwasawa

Publications and source records attributed to Y Iwasawa.

At least 55 records · Page 3Linked to original sources
PubMed1981

[Bronchodilator actions of diltiazem in vitro and in vivo (author's transl)].

Bronchodilator effects of diltiazem were investigated in the isolated guinea pig tracheal chain and in the anesthetized cat. Interaction of diltiazem with isoproterenol (iso) was also examined. Diltiazem (10(-4) g/ml) relaxed by 70% the tracheal chain contracted by histamine, 10(-5) g/ml. This effect of diltiazem was not affected by pretreatment with propranolol, 3 X 10(8) g/ml. Diltiazem (400 microgram/kg, i.v.) diminished by 20% the elevation of intratracheal pressure induced by serotonin aerosol, the effect of which lasted for approximately 20 min. On the other hand, diltiazem (10(-5) g/ml) produced no influence on the iso-induced relaxation of the guinea pig trachea. In the anesthetized dog, diltiazem (20 microgram/kg/min, i.v.) did not affect the iso-induced bronchodilation when histamine was used as a spasmogen, while the positive chronotropic action of iso was diminished. On the contrary, propranolol (30 microgram/kg, i.v.) potentiated the bronchoconstrictor effect of histamine and suppressed both the bronchodilating and positive chronotropic actions of iso. Thus, the effects of diltiazem differed from those of propranolol. In summary, diltiazem showed bronchodilation both in vitro and in vivo, although the activity was not so potent, With regard to the iso-induced bronchodilation, diltiazem had no effect at a dose which diminished the positive chronotropic action of iso.

Animals↗
PubMed1980

Evaluation of an infusion solution enriched with branched chain amino acid in parenteral nutrition of rats.

Nutritional effects of an infusion solution enriched with branched chain amino acids (BCAAs) were investigated with young adult rats. Continuous infusion through a central venous cannula was carried out for 7 days with three kinds of solutions: 1) 21.8% glucose (S-1); 2) 18.6% glucose plus 2.50% amino acids based on human milk pattern (S-2), and 3) 18.6% glucose plus 2.58% amino acids enriched with BCAAs (S-3). Rats received daily 50 ml of the solution, containing 45 kcal and 200 mg N in S-2 and S-3. The body weights of rats in the S-2 and S-3 groups were only slightly reduced, while those of the S-1 group were extremely reduced. The rats were in positive nitrogen balance in the S-2 and S-3 groups on days 2-7. Its value was somewhat, but not significantly, larger in the S-3 group than in the S-2 group. The plasma BCAA levels determined 15 minutes after the end of infusion were higher in the S-3 group than in the S-2 group, but there was no significant difference except for the leucine level. The urinary levels of creatinine and 3-methylhistidine, the plasma levels of urea and glucose, and liver lipid content were similar in the S-2 and S-3 groups. The plasma albumin level was somewhat higher in the S-3 group than in the S-2 group. The present data suggest that an infusion solution enriched with BCAAs served to maintain the normal rats in desirable nutritional status.

Amino Acids↗
PubMed1979

Plasma aspartate levels in rats following administration of monopotassium aspartate via three routes.

Plasma aspartate levels were measured after potassium aspartate administration through different routes to rats of various ages. The changes in plasma levels were most significant with intraperitoneal injection. Dose- and age-related responses to aspartate load were obtained. The present data suggest that a marked elevation of plasma aspartate levels may result in neuronal necrosis. By comparing the plasma aspartate levels with the results on hypothalamic lesion (Okaniwa et al., 1979), plasma peak value associated with the lesion was estimated in each case of various administration routes and rat ages.

Administration, Oral↗
PubMed1976

Studies on the structure activity relationship of adrenergic beta-mimetic benzylamine derivatives.

Appropriately substituted benzylamine (BZA) derivatives, fragmented derivatives of tetrahydroisoquinolines, were found to be directly acting adrenergic beta-stimulants, exhibiting tracheal relaxing, positive chronotropic and free fatty acid (FFA) releasing activities. The chemical structures essential for manifestation of the beta-action were i) 3,4-dihydroxybenzylamine, ii) arylmethyl group at position alpha, iii) lower alkyl group on the N atom. The structure activity relationships of BZA-derivatives were almost similar to, but partly different from those of tetrahydroisoquinoline- and catecholamine-derivatives. The tracheal relaxing, positive chronotropic and FFA-releasing actions of alpha-(3,4,5-trimethoxybenzyl)-N-methyl-3,4-dihydroxybenzylamine, the most active compound in the BZA-derivatives tested, were approximately one-hundred, thirty and fifty times less active than those of ISO, respectively. These results indicate that this compound is beta1-selective, while trimetoquinol is beta2-selective.

Adipose Tissue↗
PubMed1976

Studies on the mode of antagonism between adrenergic beta-mimetics and beta-blocking agents (II). Analysis by the uptake saturation model.

Curves of experimentally plotted log (dose ratio-1) vs.-log [B] for the antagonism between adrenergic beta-mimetics, isoproterenol (ISO) and trimetoquinol (TMQ), and various beta-antagonists in relaxation of guinea-pig trachea could not be reasonably fitted to Schild's equation which has been commonly used in the analysis of drug-antagonism. Taking into consideration the saturable uptake process of the drug used herein, the equation presented in this paper fitted fairly well to the experimental curves and explains the following results: 1, TMQ was more strongly antagonized than ISO by all the blocking agents tested, that is, the apparent modes of antagonism were different between ISO and TMQ although they are considered to interact with the same receptor site. 2, The slope of the curve for a given antagonist markedly differed between ISO and TMQ. It is hypothesized that ISO is more easily taken up than TMQ. This was experimentally confirmed: i.e., ISO was potentiated about 8 fold by inhibiting the uptake process with dibenamine while TMQ was not. By pretreatment with dibenamine, the log (dose ratio-1) vs.-log [B] curve for the ISO-propranolol antagonism was shifted upward and superimposed with the theoretical curve of antagonism in which uptake of the agonist was neglected.

Adrenergic beta-Agonists↗
PubMed1975

Studies on mode of antagonism between adrenergic beta-mimetics and beta-blocking agents (I). Beta-blocking action of mescaline and its derivatives.

In order to clarify whether or not trimetoquinol (TMQ) and isoproterenol (ISO) interact with the same receptor, the pA2 values of propranolol (PR) and certain trimethoxybenzene derivatives were measured, using isolated guinea pig tracheal chains. Each of PR, mescaline (MES) and its derivatives gave almost the same pA2 values for TMQ and ISO. Introduction of an alkyl group into the N atom of MES increased the affinity to the receptor in the order of methyl and isopropyl as well as the structureactivity relationship of catecholamines, while that of hydroxyl group in the beta-position of the side chain decreased pA2 values. The slopes of the regression lines for anti-TMQ action of MES derivatives as well as PR were almost one, but those for their anti-ISO action were less than 0.3. 3,4,5-Trimethoxyaniline and 3,4,5-trimethoxybenzoic acid had little activity as beta-blocking agents. These results suggest the possibility that TMQ and ISO would interact with the same receptor sites. The importance of the trimethoxybenzene and the phenethylamine moieties in the MES-derivatives for anti-TMQ action is discussed.

Adrenergic beta-Agonists↗