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Biomedical subjects

K Takeda

Publications and source records attributed to K Takeda.

At least 1,333 records · Page 74Linked to original sources
PubMed1981

[Antihypertensive effects of labetalol in three types of hypertensive models of rats (author's transl)].

Effects on blood pressure and heart rate of labetalol, a new beta-adrenoceptor blocking agent with alpha-blocking action were studied in conscious hypertensive rats (SHR, DOCA-hypertensive rats and renal hypertensive rats (RHR)). Labetalol with two asymmetric carbon atoms consists of an equal proportion of two racemates. In SHR, prevention of the development of hypertension was noted after 1.5 weeks of chronic oral administration of labetalol 25, 50 and 100 mg/kg/day, while bradycardia occurred beginning with the day of administration. Thus, the prevention of the development of hypertension appeared much earlier than in the case of the other beta-blockers. Antihypertensive effects and bradycardia were also noted in DOCA hypertensive rats and RHR after oral administration of labetalol 10, 30 and 100 mg/kg/day for six days. In DOCA hypertensive rats, the antihypertensive effect was more pronounced that in the RHR. These findings are in contrast to those with other beta-blockers. Other beta-blockers produced antihypertensive effects only in SHR. It is concluded that not only the beta-blocking action, but also the alpha-blocking action of labetalol plays an important role in the antihypertensive effects of labetalol.

Animals↗
PubMed1981

[Evaluation of CPK isoenzyme in head injury (author's transl)].

Total creatine phosphokinase (t-CPK) and its isoenzyme were measured frequently after admission in 25 case of head injuries. Interesting changes of CPK were detected especially in initial stage. T-CPK increased up to 3-4 days after admission and subsided to normal level within 2 weeks. CPK-BB was demonstrated in 15 cases, and the elevated CPK-BB disappeared within 24 hours in most cases. In relation to the findings of computed tomography (CT), CPK-BB was demonstrated more frequently in the cases showing complex of high density area (HDA) and low density area (LDA) or LDA only, than in those showing HDA.

Brain Injuries↗
PubMed1980

Ultrastructure of intracytoplasmic membranes of Methanomonas margaritae cells grown under different conditions.

The development of intracytoplasmic membranes of Methanomonas margaritae cells grown under different culture conditions was studied. Growth on methane was strongly accelerated by the addition of copper ions. Acceleration by copper, however, was not observed in the case of growth on methanol. Cells grown on methane with copper possessed intracytoplasmic membranes along the cell periphery. When the the organism was grown in a medium lacking copper, intracytoplasmic membranes appeared as large vesicles surrounded by a unit membrane at the periphery of the cell. The vesicles originated from paired membranes due to the absence of copper in the medium. Cells grown on methanol with or without copper possessed a number of vesicles of different sizes arranged in a chain along the cell periphery. The possible relationship between membrane arrangement and methane oxidation is discussed.

Copper↗
PubMed1980

Possible mechanisms for inotropic actions of vanadate in isolated guinea pig and rat heart preparations.

The mechanism of inotropic actions of vanadate studied in isolated, electrically stimulated atrial and ventricular muscle preparations of rat or guinea-pig heart. Vanadate produced a negative inotropic effect in guinea-pig left atrial preparations associated with a marked shortening of the action potential plateau. In guinea-pig papillary muscle, or rat atrial or ventricular muscle preparations, vanadate produced a positive inotropic effect, which was not affected by either propranolol, phentolamine or metiamide. The positive inotropic effect was observed when action potential duration was either increased or decreased. Inotropic concentrations of vanadate failed to significantly alter the ouabain-sensitive 86Rb+-uptake, an estimate of sodium pump activity, or tissue concentration of cyclic AMP in electrically stimulated preparations. In partially depolarized rat atrial preparations in which fast sodium channels were inactivated in the presence of a high concentration of K+ (22 mmol/l), vanadate restored electrical activity (calcium-dependent action potentials) and the contraction, similar to isoproterenol. This action of vanadate was abolished by Mn2+, a slow channel inhibitor, but not by tetrodotoxin. The characteristic of vanadate- and isoproterenol-restored preparations, however, were substantially different. Moreover, vanadate failed to restore the contraction or action potential in partially depolarized guinea pig atrial preparations unlike isoproterenol. These results indicate that vanadate may either enhance or inhibit slow channels in cardiac muscle.

Action Potentials↗
PubMed1980

Effects of ammonium ions on endplate channels.

Miniature endplate currents, recorded from voltage-clamped toad sartorius muscle fibers in solutions containing ammonium ions substituted for sodium ions, were increased in amplitude and decayed exponentially with a slower time constant than in control (Na) solution. The peak conductance of miniature endplate currents was also greater in ammonium solutions. The acetylcholine null potential was -2.8 +/- 0.8 mV in control solution, and shifted to 0.9 +/- 1.6 mV in solutions in which NH4Cl replaced half the NaCl. In solutions containing NH4Cl substituted for all the NaCl, the null potential was 6.5 +/- 1.3 mV. Single channel conductance and average channel lifetime were both increased in solutions containing ammonium ions. The exponential relationship between the time constant of decay of miniature endplate currents or channel lifetime and membrane potential was unchanged in ammonium solutions. A slight but consistent increase in peak conductance during miniature endplate currents and single channel conductance was seen as membrane potential became more positive (depolarized) in both control and ammonium solutions. Net charge transfer was greater in ammonium solutions than in control solution, whether measured during a miniature endplate current or through a single channel. The results presented here are consistent with an endplate channel model containing high field strength, neutral sites.

Ammonium Chloride↗
PubMed1980

Effect of methyl substitution on mutagenicity of 2-aminodipyrido.

The mutagenicities of 2-aminodipyrido [1,2-a:3',2'-d] imidazole (Glu-P-2, a mutagen obtained from pyrolysate of glutamic acid) and six methyl substituted derivatives of Glu-P-2 were tested with Salmonella typhimurium TA98 and TA100 with S-9 mix. Glu-P-1 (6-Me-Glu-P-2) was the strongest mutagen to TA98 and TA100. 3-Me-Glu-P-2 was weakest. The presence of a methyl group, and its position were shown to affect the mutagenicity significantly.

Imidazoles↗
PubMed1980

Radiological diagnosis of acute gastric anisakiasis.

The radiological and clinical features of 41 cases of acute gastric anisakiasis, a form of visceral larva migrans caused by eating poorly cooked fish containing Anisakis larvae, are reviewed. The most important radiological finding, present in 31 patients (76%), was the demonstation of a thread-like filling defect approximately 30 mm long. Suggestive but indeterminate findings such as coarse, broad gastric folds due to mucosal edema were demonstrated in 10 patients (24%). In no case was the radiological examination negative. Once the presence of this larva is suspected, it can often be demonstrated radiologically using careful technique and interpretation.

Adult↗
PubMed1980

Effect of sodium loading and depletion on vascular reactivity and prostacyclin generation.

In order to estimate the modulatory activity of Prostacyclin (PGI2) to the vascular reactivity, pressor responses to angiotensin II (A II) and noradrenaline (NA) and PGI2 generation aorta were measured using the rats of sodium loading or of sodium depletion. On the sodium loading, the blood pressure increased gradually and plasma renin activity (PRA) and plasma aldosterone concentration (PAC) were decreased. The pressor responses to A II and NA were enhanced by sodium loading. The PGI2 generation of aorta was enhanced at the initial stage of sodium loading and decreased thereafter. The increased generation of PGI2 may represent the adaptive mechanism for the attenuation of the sustained elevation in blood pressure. It sodium depletion, the pressor responses to A II and NA were decreased, and PRA and PAC were elevated. PGI2 generation of aorta was also increased. These findings suggested that PGI2 could participate in blood pressure control mechanism on sodium loading and depletion.

Aldosterone↗