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Biomedical subjects

T Mayahara

Publications and source records attributed to T Mayahara.

10 recordsLinked to original sources
PubMed1982

Effects of methylxanthines on superprecipitation of myosin B extracted from rabbit fast skeletal muscle.

Myosin B was extracted from rabbit fast skeletal muscle. Caffeine (2-70 mM), theophylline (2-30 mM), and theobromine (2 mM) were examined for their effects on the rate and extent of myosin B superprecipitation at a low ionic strength (50 mM KCl) and a low concentration of ATP (40 microM) by the turbidimetric method. The rate of the superprecipitation was significantly (p less than 0.05 and p less than 0.01) reduced by 30-70 mM caffeine and 2-30 mM theophylline, while the extent was significantly (p less than 0.01) increased by 10-30 mM theophylline. The onset of the superprecipitation was also delayed and a clearing phase was even induced by 50-70 mM caffeine. Theobromine had no significant effect on the rate or extent of the superprecipitation at the concentration used. These results indicate that caffeine and theophylline are retardants of the myosin B superprecipitation reaction in the concentration ranges investigated.

Animals↗
PubMed1982

Modification of calcium fluxes by dimethyl sulfoxide and 2-butoxyethanol in sarcoplasmic reticulum vesicles: a possible mechanism for skeletal muscle relaxation induced by dimethyl sulfoxide.

In order to investigate the mechanism of skeletal muscle relaxation induced by dimethyl sulfoxide, 2-butoxyethanol and dimethyl sulfoxide were examined for their effects on 1) Ca2+ uptake into and efflux from sarcoplasmic reticulum vesicles prepared from rabbit fast skeletal muscle and crayfish tail muscle by the murexide method, 2) ATPase activities of rabbit reticulum vesicles, 3) the isolated phrenic nerve-diaphragm preparation of the rat and 4) crayfish opener muscle preparation. Ca2+ efflux rate from rabbit reticulum vesicles was markedly decreased with increasing concentrations (5-20% v/v) of dimethyl sulfoxide without affecting the maximum Ca2+ uptake by the reticulum. 2-Butoxyethanol showed quite contrary effects. Dimethyl sulfoxide strongly inhibited the activity of basal ATPase rather than of Ca2+-dependent ATPase. 2-Butoxyethanol did not significantly inhibit the activity of basal ATPase, but markedly increased Ca2+-dependent ATPase activity. Antagonisms between dimethyl sulfoxide and caffeine were demonstrated either in contractions of crayfish opener muscles or in the Ca2+ release from crayfish sarcoplasmic reticulum vesicles. These results indicate a possibility that dimethyl sulfoxide reversibly induces skeletal muscle relaxation mainly in the sarcoplasmic reticulum by means of decreasing the rate and the amount of Ca2+ release from the reticulum.

Adenosine Triphosphatases↗
PubMed1979

[Automatic adder mixer for photometric cells: application to superprecipitation of myosin B. (author's transl)].

An automatic adder mixer for photometric cells was newly developed in our laboratory and was applied in experiments of superprecipitation of myosin B. The mixer has a reciprocating blade-type impeller with a pit for loading samples. The pit was cut so as to be just above the meniscus of the solution in a cell at the top dead point of the cam mechanism and so as to enter the solution at the bottom dead point. When 10 microliter of methylene blue solution was added, the mixing time was 0.6 sec. Myosin B was extracted from rabbit white muscle. Adding ATP (1 mM) to myosin B suspension and mixing was carried out by hand, using a mixing plunger, and also using the automatic adder mixer. The recordings obtained were then compared. Continuous recording of the initial reaction was successfully obtained only when the automatic adder mixer was used. Excellent results were also obtained with respect to reproducibility. The automatic adder mixer is easy to make, inexpensive, and can be utilized in conjunction with conventional spectrophotometers.

Chemical Precipitation↗
PubMed1978

[Digestant effects of a new digestive enzyme capsule, Excelase, on jejunectomized and pancreato-jejunectomized Beagle dogs (author's transl)].

The digestant effects of a new digestive capsule, excelase containing sanactase, proctase, meicelase, olipase-2S and pancreatic digestive enzyme TA, were investigated in vivo. Jejunectomy and pancreato-jejunectomy were performed to cause an artificial disturbance of gastro-intestinal digestion and absorption in Beagle dogs. Absorption of protein and fat was measured using chromic oxide as an indicator. Excelase (3 capsules/dog/day) was given orally to Beagle dogs 1 week after each operation for 7 weeks. Changes in body weight and absorption of protein and fat were observed during the administration. The decrease in body weight of dogs treated with excelase fully recovered, however, that of controls remained even 8 weeks after the surgery. Absorption of protein and fat in the groups of dogs treated with excelase was greatly improved as compared with controls. The digestant effects of excelase on percent absorption of protein and fat were more manifest in pancreato-jejunectomized dogs than in jejunectomized dogs. These results indicate that excelase is effective for gastro-intestinal disturbances of digestion and absorption. The digestant effects of excelase on starch, protein and cellulose were also investigated in vitro using a gastro-intestinal model.

Animals↗