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T Totsuka

Publications and source records attributed to T Totsuka.

89 records · Page 5Linked to original sources
PubMed1978

Involvement of calcium in cyclic nucleotide metabolism in human vascular smooth muscle.

When cyclic nucleotide phosphodiesterase was purified from isolated smooth muscle layer of human aorta by DEAE-cellulose column chromatography, separated cyclic GMP phosphodiesterase activity was markedly stimulated in the presence of 10-20 micrometer of Ca2+ by a protein modulator which has similar physicochemical properties to troponin C. Synthetic compound, N-(6-aminohexl)-5-chloro-1-naphthalensulfonamide, which produced relaxations of arteries contracted by prostaglandin F2alpha or KCl was found to inhibit selectively this Ca2+-dependent cyclic GMP phosphodiesterase. This compound produced inhibition of superprecipitation of myosin B system obtained from mouse skeletal muscle and also inhibited adenosine triphosphatase activity of myosin B. Our data suggest that calcium is involved through a protein modulator in cyclic nucleotide metabolism of vascular smooth muscle and that the calcium-dependent protein modulator probably participates in the regulation of contractile response of vascular smooth muscle by affecting actomyosin ATPase activity.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1978

A novel vascular relaxing agent, N-(6--aminohexyl)-5-chloro-1-naphthalensulfonamide which affects vascular smooth muscle actomyosin.

The relaxing effect and possible mechanism of N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7) on isolated rabbit artery were investigated. The addition of W-7 in concentrations ranging from 1 X 10(-6) to 3 X 10(-4) M caused a significant relaxation of isolated rabbit vascular strips contracted by KCl, prostaglandin F2alpha, norepinephrine, histamine, CaCl2, serotonin or angiotensin II. W-7 also caused a shift to the right of the dose-response curves for all agonists tested. Propranolol and atropine did not affect W-7 induced relaxation, suggesting that this drug does not act through beta adrenergic or cholinergic receptors. Superprecipitation of actomyosin from bovine aorta smooth muscle was inhibited by the addition of W-7 in a dose-dependent fashion. The concentration of W-7 which inhibited superprecipitation of bovine aorta smooth muscle actomyosin was in good agreement with the dose producing relaxation of isolated vascular strips. These facts suggest that W-7 produces relaxation of isolated vascular strips by inhibiting actin and myosin interaction.

Actomyosin↗
PubMed1975

Electric birefringence of myosin subfragments.

Electric birefringence measurements have been made on aqueous solutions of myosin subfragments, heavy meromyosin, subfragments 1 and 2 (S-1 and S-2). All of these showed positive electric birefringence. Heavy meromyosin and S-2 showed a large intrinsic Kerr constant. From the analysis of the build up and decay process of the birefringence, the contribution of the slow induced dipole moment was concluded in heavy meromyosin and S-2, although the existence of the permanent dipole moment was not completely excluded. The decay process of the birefringence of heavy meromyosin was found to consist of two components; the fast one of which had a relaxation time of the same order as that of S-1. This is probably due to the presence of a flexible hinge in heavy meromyosin.

Adenosine Triphosphate↗
PubMed1975

Protein and RNA synthesis in the skeletal muscle of hereditary dystrophic mouse.

Protein and RNA contents in muscle of normal and hereditary dystrophic mice C57BL/6J-dy/dy were reexamined on the basis of DNA. It was observed that protein and RNA contents in dystrophic muscle decreased at the early stage of the disease, in disagreement with the reported results on a wet weight basis, in which RNA content in dystrophic muscle had been found to increase. Rates of protein and RNA systhesis in the early stage of the disease were also determined with a concomitant check of the specific activities of free amino acids and free nucleotides. The rates of both protein and RNA synthesis (i.e., specific activities of protein and RNA) were higher in the dystrophic muscle, but when they were expressed on a DNA basis, the total protein synthesis per cell was the same as that of normal muscle and the total RNA synthesis per cell showed a smaller increase in dystrophic muscle. These apparent increases of protein and RNA synthesis were discussed in connection with the decreased protein and RNA contents in the cells of dystrophic muscle. The synthesized RNAs seemed to contain mRNA on the basis of sedimentation character and Millipore filter binding ability. However, no particular RNA was mainly synthesized in dystrophic muscle.

Amino Acids↗
PubMedDate not supplied

Recycling process of acetylcholine in the rat muscle controlled in a short-term memory manner.

The recycling process of acetylcholine (ACh) was studied in reference to muscle potentials evoked by sciatic stimuli in the presence of neostigmine. Wistar rats around 20 days old were anesthetized with urethane. Muscle potentials were recorded with concentric electrodes from their exposed medial gastrocnemius muscles before and after the injection of neostigmine. Attention was paid to changes in muscle potentials evoked by a set of 3 stimuli, and comparison was made mainly between successive two sets. Three potentials before neostigmine treatment were similar in amplitude. When a set of 3 stimuli was delivered 8 min after it, the first potential was as large as that before it. The others were greatly depressed. The first potential evoked by a set of 3 stimuli 10 min after neostigmine treatment showed a similar amplitude to the control level. The other potentials were again reduced severely. However, none of them were depressed so much when 3 stimuli were delivered 11 min after the drug application. When two sets of 3 stimuli were given with an interval of one minute, it was repeatedly observed in all animals that muscle potentials evoked by the second set were influenced by the first set. The second potential evoked by the second set was not so much depressed as seen when the interval was two or more minutes. Thus, a striking contrast was observed between successive two sets of 3 stimuli with an interval of one minute. These results indicate that the recycling process of ACh was activated following impulse transmission in rat muscles, and suggest that there exists such a neural mechanism as can exert an influence on the process in a short-term memory manner.

Acetylcholine↗
PubMedDate not supplied

Neostigmine-induced characteristics of spontaneous activities and evoked muscle potentials in rat gastrocnemius and soleus muscles.

Using concentric electrodes, spontaneous activities and evoked muscle potentials were recorded from medial gastrocnemius (MG) and soleus (SOL) muscles of Wistar rats about 60 days old. When neostigmine methylsulfate was injected, spontaneous activity such as motor unit discharges occurred in a burst in the MG muscles, in contrast to few activity before the injection of this drug. In the SOL muscles, only single spikes were sometimes observed after it. In coincidence with burst discharges, some oscillations were definitely observed following the main component of MG potentials evoked by single stimuli to a sciatic nerve, whereas only slight deflections could be detected in SOL potentials. Thus, different modification of spontaneous activities and evoked muscle potentials were induced in MG and SOL muscles by the injection of neostigmine methylsulfate.

Animals↗
PubMedDate not supplied

Different changing patterns of soleus potentials due to repetitive stimulation in young and old rats.

Time courses of changes in medial gastrocnemius (MG) and soleus (SOL) muscle potentials induced by repetitive stimulation at 5 Hz were studied using Wistar strain rats. Particular interest was focussed on the changing pattern of SOL potentials in old rats as compared with that in young ones. Contrary changing patterns of SOL potentials were found in young and old rats. SOL potentials were rapidly reduced to respective plateau levels in old rats while they were gradually potentiated in young ones when 5 Hz stimulation was given for 10 min. Moreover, the pattern obtained from middle aged rats fell between those of the two age-groups.

Aging↗
PubMedDate not supplied

A secondary aortoenteric fistula, successfully treated with proper preoperative diagnosis.

A rare case, presented as a secondary aortoenteric fistula after an abdominal aortic aneurysmectomy with Y-graft replacement 9 months earlier, is reported. The course was clinically very unique, in that the first manifestation of the aorto enteric fistula occurred while the patient had already been hospitalized after the orthopaedic surgical treatment for the pyogenic vertebral spondylitis. After the episode of gastrointestinal bleeding, radiological studies were promptly collected, and with the proper diagnosis, a successful surgical treatment was given under the stable hemodynamic condition, and the patient recovered uneventfully. Retrospectively considered, there are several findings that would suggest that seemingly a secondary aorto enteric fistula could have resulted from an early process of the primary aorto enteric fistula having been under progress without any detectable manifestations before the previous aneurysmectomy. The diagnostic values of computed tomography and the scintigraphy for this rare clinical entity is also underlined.

Aged↗