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Biomedical subjects

H Koike

Publications and source records attributed to H Koike.

At least 361 records · Page 20Linked to original sources
PubMed1980

Effects of CS-611 on the electrophysiological properties of canine cardiac tissues.

Effects of CS-611, a new coronary vasodilator, on the electrophysiological properties of Purkinje fibers, auricular and ventricular muscles isolated from dogs were examined with a microelectrodfe technique. CS-611 between 3 X 10(-6) and 3 X 10(-5) g/ml shortened the action potential duration (APD) of each tissue, especially of Purkinje fibers, without any significant alterations in the resting membrane potential, action potential amplitude and maximum rate of rise (V max). CS-611 also shortened the effective refractory period (ERP) of Purkinje fibers and ventricular muscles, but to a lesser extent than APD, resulting in an increase of ERP/ADP. The level of membrane potential needed to elicit premature excitation in Purkinje fibers and Vmax of the earliest response tended to increase in the presence of CS-611. CS-611 partially restored the reduced Vmax of Purkinje fibers exposed to hypoxia. The spontaneous firings in Purkinje fibers were decreased or abolished by CS-611. The possible role of these effects of CS-611 in its antiarrhythmic action was discussed.

Action Potentials↗
PubMed1979

Free amino acids in motor cortex of amyotrophic lateral sclerosis.

Free amino acids were estimated quantitatively in the motor cortex from 3 patients with amyotrophic lateral sclerosis (ALS) and 11 control subjects. Among 7 amino acids which showed statistically significant changes, taurine was the only one which was increased constantly and most markedly in the motor cortex of all the 3 ALS cases. It was suggested that the metabolism of sulfur amino acids might be affected in comparatively early stages of ALS.

Adult↗
PubMed1979

Intra-axonal diffusion of [3H]acetylcholine and [3H]gamma-aminobutyric acid in a neurone of Aplysia.

1. [3H]acetylcholine (ACh) or [3H]gamma-aminobutyric acid (GABA) was injected into the cell body of a cholinergic neurone of Aplysia kurodai. 2. [3H]ACh moved down the axon at a maximum speed of 2.5 mm/sec at 20 degrees C. 3. 20 mM-colchicine suppressed this movement, but some passive movement of radioactivity was noted along the axon. 4. Profiles of the passive movement coincided with theoretically obtained diffusion profiles. 5. The diffusion coefficient of ACh in the axoplasm was estimated. It was 3 x 10(-6) cm2/sec at 5 degrees C, 4 X 10(-6) cm2/sec at 15 degrees C and 6.5 x 10(-6) cm2/sec at 30 degrees C. The Q10 was 1.35, the activation energy was about 5 kcal/degrees C. These diffusion coefficients were lower than that of free diffusion of ACh (8 x 10(-6) cm2/sec at 18 degrees C, Fatt, 1954), and assumed to be reasonable, if one considers frictional resistivity of axoplasm in the diffusion of ACh molecules. 6. [3H]GABA diffused similarly to ACh, and the diffusion coefficients agreed with the estimated value when the molecular size differences were taken into account. 7. Both ACh and GABA seemed to diffuse in soluble form or as single molecules in the axoplasm. 8. Intra-axonal diffusion is very effective for short distances.

Acetylcholine↗
PubMed1979

Antiarrhythmic activity of dextro- and levo-isomers of 5-methyl-8-(2-hydroxy-3-t-butylamino-propoxy) coumarin hydrocholoride (bucumolol), a beta-adrenergic blocking agent, on aconitine-induced atrial and ouabain-induced ventricular arrhythmias in dogs.

The beta-blocking, antiarrhythmic, and local anesthetic effects of the racemic mixture and optical isomers of bucumolol, 5-methyl-8-(2-hydroxy-3-t-butylamino-propoxy) coumarin hydrochloride, were studied in dogs, guinea-pigs and frogs. In blocking the positive chrontropic response to isoproterenol, the levo-isomer of bucumolol was about 40 times more potent in dogs, and 270 times in guinea-pigs than its dextro-isomer and twice as effective in both species as the racemic mixture. In frog sciatic nerves bucumolol was 1/10-1/15 as potent in local anesthetic action as propranolol on a weight basis. Dextro- and levo-isomers and racemic bucumolol neither elevated electrical threshold for propagated impulses nor prolonged the effective refractory period of the dog right atrium. The levo-isomer and racemic bucumolol were capable of suppressing aconitine-induced atrial arrhythmia, while the dextro-isomer was less effective. Both isomers and racemic bucumolol were capable of reversing ventricular arrhythmia caused by ouabain, but the effective dose of the levo-isomer was significantly less than that of the dextro-isomer. The results suggest that both specific beta-blocking activity and non-specific membrane action of bucumolol suppressed experimental arrhythmias in dogs produced by aconitine and ouabain.

Aconitine↗
PubMed1977

Spinal myoclonus with dermal and retinal changes affected by myelitis.

Intermittent, rhythmical myoclonus that had been present in the lower limbs of a 68-year-old man for more than 50 years was obviously increased in frequency during the period when the patients suffered from acute transverse myelitis. The same type of movements were readily induced by irrigation of the urinary bladder during the period of paraparesis. Removal of some possible inhibitory influences from a myoclonic focus in the lower spinal cord with resulting heightened excitability was thought to be the mechanism of these phenomena, although direct irritation of the myoclonic focus by the inflammatory process was also conceivable. The patient had keratosis palmoplantaris hereditaria and retinal pigment degeneration, suggesting the possibility of a congenital neuroectodermal dysplasia.

Action Potentials↗
PubMed1976

Coordination chemical studies on metalloenzymes. Kinetics and mechanism of the Zn(II) exchange reaction between chelating agent and apo-bovine carbonic anhydrase.

The mechanism of removal of the zinc ion from bovine carbonic anhydrase [EC 4.2.1.1] (BCA) by a chelating agent was studied. It was shown that the removal of the zinc ion from BCA took place through the formation of a ternary complex involving the enzyme, chelating agent, and metal ions. The formation constant of the ternary complex (KEML) was 10(2) M-1. This value was lower than the formation constant assumed by Wilkins. The reaction of zinc-2, 6-pyridinedicarboxylate complex with the apoenzyme also took place through the formation of the ternary complex and the species which reacted with apo-BCA was a 1:1 complex of zinc and 2, 6-pyridine-dicarboxylate. The theoretical equilibrium equation derived from the reaction mechanism showed a good fit with observed equilibrium dialysis data.

Animals↗