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Biomedical subjects

T Tsukada

Publications and source records attributed to T Tsukada.

At least 343 records · Page 19Linked to original sources
PubMed1977

Antiarrhythmic and electrophysiological effects of CH-200.

A new antiarrhythmic drug CH-200, 5-phenacyl-thieno[3,2-c]yridinium, was compared with procainamide and lidocaine in a two-stage coronary ligation arrhythmia model for its efficacy and electrophysiological properties. CH-200 suppressed arrhythmia in beagle dogs more effectively than did procainamide and lidocaine. The antiarrhythmic effects of CH-200 and procainamide developed slowly and lasted longer than those of lidocaine. Electrophysiological studies with CH-200 showed that it decreased max dV/dt of the action potential. This effect was dependent on the heart rate: the higher the rate, the stronger the effect. CH-200, procainamide and lidocaine prolonged the effective refractory period and this effect seemed to be responsible for suppressing the arrhythmia after coronary ligation. CH-200 and procainamide increased the frequency of ventricular pacemaker activity, while lidocaine decreased it. These effects appear to be unimportant for the antiarrhythmic effects.

Acetophenones↗
PubMed1977

[Effects of a new adrenergic beta-blocking agent, Kö 1400 on the canine heart-lung preparation supported by a donor dog and the perfused hindlimb preparation of the dog (author's transl)].

Using the canine heart-lung preparation supported by a donor, effects of a new adrenergic beta-blocking agent, dl-1-(tert. butylamino)-3-[ (2-propinyloxy) phenoxy]-2-propanol hydrochloride (Kö 1400), on cardiac function, myocardial metabolism, and coronary circulation were studied and compared with those of propranolol. Effects of this substance on the peripheral vascular bed were also studied in the perfused hindlimb preparation of the dog. Kö 1400 produced a positive inotropic and chronotropic effect. Mechanical efficiency of the heart improved after Kö 1400, while it lessened after propranolol. A decrease in the coronary flow was observed in association with a slight increase in myocardial O2 consumption, indicating that the substance exerted a direct constrictive effect on the coronary vasculature. As a beta-blocker, Kö 1400 was found to be 2-3 times more effective than propranolol. The uptake of the free fatty acid (FFA) by the heart was increased by Kö 1400 and the myocardial redox potential improved. In the perfused hindlimb preparation, intraarterial injection of Kö 1400 resulted in a transient increase of the femoral blood flow for a decrease in the flow followed by a sustained decrease. With repeated administration a marked tachyphylaxis was observed.

Adrenergic beta-Antagonists↗
PubMed1976

[Experimental anti-arrhythmic effects of a new beta-adrenergic receptor blocking agent, dl-l-(tert. butylamino)-3-[(2-propinyloxy)phenoxy]2-propanol hydrochloride (dl Kö 1400-Cl)].

Antiarrhythmic property of a new adrenergic beta-blocking agent, dl-1-(tert.butylamino)-3[(2-propinyloxy) phenoxy]-2-propanol hydrochloride (Kö 1400-Cl) was studied, using 1) ouabain-induced arrhythmia in the guinea pig, 2) aconitine-induced arrhythmia in the rat, 3) arrhythmia induced by two-step ligation of coronary artery (Harris's method) in the dog and 4) halothane-adrenaline arrhythmia in the dog and was compared with those of propranolol, oxprenolol, procainamide and ajmaline. Procainamide and ajmaline produced a marked protective effect against aconitine-induced ventricular extrasystole, but were not so effective against aconitine-induced ventricular fibrillation, while oxprenolol and, to a lesser degree, propranolol were effective against the latter type of aconitine arrhythmias. Kö 1400-Cl proved to be ineffective. All the compounds tested produced a marked protective action against ouabain-arrhythmia. Whereas procainamide was most effective in abolishing the ventricular arrhythmia due to coronary-ligation even on the first postoperative day, Kö 1400-Cl and propranolol were almost ineffective on the first day. Even on the second postoperative day, the antiarrhythmic effects of these two beta-blockers were not remarkable, effective only in 2/4 animals in the case of Kö 1400-Cl and in 2/3 animals in the case of propranolol. On the contrary, all the beta-blockers tested produced a protective action against halothane-adrenaline arrhythmia at much lower doses than against coronary ligation arrhythmia. The potency ratio of Kö 1400-Cl and propranolol was 3 : 1, which paralleled with beta-blocking activity of these compounds.

Aconitine↗
PubMed1975

[The relations between lactation and cyclic-AMP -- The influences of adenyl cyclase activity on casein biosynthesis ability in the organ culture of the mouse mammary gland (author's transl)].

The relationships between hormonal action and cyclic AMP as the second messenger of hormones have recently been discussed on many hormones. Lactation is influenced by various hormone, especially, insulin, prolactin, and hydrocortisone. Whether adenyl cyclase activity in the mammary gland of mouse epithelial cells has parallel relations with casein biosynthesis ability or not was examined using the mammary gland organ culture method. Female, mid-pregnant (11-14 days), mice of DDY strain were used. Organ culture was done by the Chen's floating lens' paper method, using the hormone-added MEM media and non-added ones. Casein biosynthesis ability was measured by observing 32P incorporation into the casein molecules. Adenyl cyclase activity was estimated by the amount of 14-C-cyclic AMP produced out of adenine-8-14C by the Kuo and Krishna's method. Radio isotope compounds were pulsed for 4 hours in the medium. The experiments revealed that the added hormones had a remarkable effect on caein biosynthesis ability, but none on adenyl cyclase activity. No parallel fluctuation was observed between adenyl cyclase activity and casein biosynthesis ability, that is, the change of adenyl cyclase activity was found to have nothing to do with casein biosynthesis ability. Consequently, the cyclic AMP addition to the media showed no effect on casein biosynthesis ability.

Adenylyl Cyclases↗