PubMed Health⌕ Search

Biomedical subjects

R Ogata

Publications and source records attributed to R Ogata.

At least 37 records · Page 2Linked to original sources
PubMed1997

Membrane currents evoked by histamine in rabbit basilar artery.

The membrane current evoked by histamine in isolated smooth muscle cells from rabbit basilar artery was investigated using the perforated-patch technique. When 10 microM histamine was applied in the bath at a holding potential of -60 mV, an inward current (79.2 +/- 55.8 pA) was transiently activated. An outward current was additionally evoked by 10 microM histamine when the membrane was held at -40 mV or less negative potentials. The outward but not the inward current was completely blocked by 100 nM charybdotoxin. A higher concentration of histamine (30 microM) failed to produce the inward current (3.4 +/- 4.8 pA) when Cl- concentration in the pipette was reduced. The apparent reversal potential of the inward current induced by histamine in physiological salt solution, in high-tetraethylammonium (TEA+) solution (bath), or in low-Cl- solution (pipette) was -6.3 +/- 4.4, -7.5 +/- 4.9, or -45.8 +/- 8.5 mV, respectively. Niflumic acid (100 microM) reversibly blocked the inward current, which was also blocked by 10 microM pyrilamine but not by 10 microM cimetidine. When histamine was continuously applied in the bath, spontaneous transient inward currents were generated. Removal of external Ca2+ or addition of 1 microM nicardipine or 2 mM caffeine reduced the amplitude of the histamine-induced inward current. These results suggest that histamine induces an inward current via H1 receptors at the resting membrane potential, possibly due to activation of Cl- currents. The Cl- inward current might be generated by elevation of intracellular Ca2+ via histamine receptors. The inward current may also contribute to control of the Ca2+ influx via a change in the membrane potential.

Animals↗
PubMed1996

Effects of calciseptine on unitary barium channel currents in guinea-pig portal vein.

Effects of synthesized calciseptine (CaS), found naturally in the venom of the black mamba, on voltage-dependent Ca2+ channels in smooth muscle cells of the guinea-pig portal vein were investigated. In the whole-cell voltage-clamp configuration, extracellular application of CaS (>/= 10 nM) inhibited the inward current in a concentration- and voltage-dependent manner at a holding potential of -90 mV. The Ca2+ current recorded at a high holding potential (-50 mV) was approximately 8 times more sensitive to CaS than that at a more negative holding potential (-90 mV). CaS (50 nM) shifted to the left the steady-state inactivation curve obtained by using single 8-s conditioning pulses of various amplitudes. When CaS (>/= 200 nM) was present in the pipette, the Ca2+ current remained for the duration of the experiments (more than 60 min) in the whole-cell configuration. Two different Ca2+ channel conductances are present in this tissue (25-pS and 12-pS channels). Both channels are blocked by dihydropyridine (DHP) derivatives, but have different sensitivities. In the cell-attached condition, CaS hardly changed the activity of either unitary Ca2+ channel current. To prevent the "run down" of the Ca2+ channels in cell-free conditions, we added cardiac cytosol, a supernatant from homogenized cardiac cells and an endogenous Ca2+ channel activating factor, in the pipette. The unitary Ca2+ channel currents were then recorded using the outside-out membrane patch configuration. Application of CaS (1 microM) in the bath completely blocked the open events of the 25-pS Ca2+ channel. CaS (10 nM) in the bath reduced the mean open time and channel availability, resulting in a decrease in the open probability of the 25-pS channel currents without affecting the amplitude of the single-channel conductance. CaS also reduced the open probability (though less potently) and channel availability of the 12-pS Ca2+ channel without a change in its amplitude. From these results, we conclude that CaS has inhibitory effects on the voltage-dependent Ca2+ current that are similar to those of DHP derivatives and that it acts from the outside of the membrane.

Animals↗
PubMed1996

Oestradiol-induced relaxation of rabbit basilar artery by inhibition of voltage-dependent Ca channels through GTP-binding protein.

1. Effects of oestradiol on the electrical and mechanical properties of the rabbit basilar artery were investigated by use of microelectrode, patch-clamp and isometric tension recording methods. 2. Oestradiol (10 nM-100 microM) relaxed arterial tissue pre-contracted by excess [K]o solution (30 mM) in a concentration-dependent manner. In Ca-free solution, histamine (10 microM) and caffeine (20 mM) each produced a phasic contraction, but oestradiol (10 microM) did not significantly affect their amplitude. 3. Oestradiol (< or = 100 microM) did not change the resting membrane potential of the artery whether in the presence or absence of TEA (10 mM). Action potentials observed in the presence of 10 mM TEA were abolished by oestradiol (100 microM). 4. Oestradiol (1 microM-100 microM) inhibited the voltage-dependent Ba current in a concentration-dependent manner. Oestradiol (100 microM) inhibited the Ba current observed in the presence of nicardipine (1 microM) more than that in the absence of nicardipine (to 31.0% vs 62.0% of control). 5. GTP gamma S (30 microM) in the pipette enhanced the inhibitory actions of oestradiol on the Ba current. On the other hand, with GDP beta S (1 mM) in the pipette, oestradiol failed to inhibit the Ba current. Pertussis toxin (PTX 3 micrograms ml-1) in the pipette totally prevented the inhibitory action of oestradiol on the Ba current. 6. Oestradiol (< or = 100 microM) had no significant effect on the outward K currents evoked by a membrane depolarization. 7. These results strongly suggest that oestradiol relaxes arterial tissue by inhibition of voltage-dependent Ca channels and that it inhibits both nicardipine-sensitive and -resistant Ca currents via a PTX-sensitive GTP-binding protein. The main target of oestradiol among the arterial Ca channels seems to be the nicardipine-resistant Ca channel, rather than the nicardipine-sensitive one.

Animals↗
PubMed1993

[Changes in bone and lipid metabolisms following oophorectomy and effects of estrogen replacement therapy].

The bone and lipid metabolisms in Japanese oophorectomized (OVX) women and effects of estrogen replacement therapy (ERT) were investigated. Three hundred and two OVX women (mean age of 41.6) and 164 premenopausal women (mean age of 42.1) were examined. BMD of the lumbar spine, serum Ca, P, Al-p, total cholesterol (T-C), HDL-C and LDL-C were measured every three months. BMD within 2 years after OVX was not significantly decreased. The mean BMD between 2 and 5 years or over 10 years after OVX was 0.83 (p < 0.01) and 0.69 (p < 0.001), respectively. Serum Ca and P were increased for 2 years and Al-p was increased for 10 years after OVX. To investigate the effect of ERT on BMD, OVX women were divided into 3 groups: ERT, VD3 and no treatment groups. After 12 months of treatment, the mean % BMD in each group was 102.9, 100.6 and 97.8, respectively. T-C or LDL-C was gradually increased in 10 years after OVX. After 15 months of ERT, the mean percentages HDL-C and LDL-C in hyperlipidemic women (LDL-C > or = 150) were 110.5 (p < 0.05) and 75.2 (p < 0.001). ERT may be requisite for OVX women and effective in preventing increased bone turnover and hyperlipidemism following OVX.

Adult↗
PubMed1991

[Early stellate ganglion block failed to prevent progress of facial nerve palsy in a patient with Ramsay-Hunt syndrome--a case report].

A 73-year-old man complained of pain in his right ear with vesicular lesion for three days. He complained of no weakness of facial musculatures, but muscle test revealed slight weakness in orbital and oral muscles on admission. His hearing acuity of the left ear was intact. Vertigo with spontaneous nystagmus to left was complained. The patient was treated with stellate ganglion block four times a day, prednisolone 80 mg a day p.o. and acyclovir i.v. Mannitol solution 300 ml a day for eight days was given i.v. to reduce edema and to protect facial nerve. On his 3rd hospital day, his paralysis progressed and he could not close his eye or whistle with his mouth. Evoked myogram showed 91% impairment of the nerve. During recovery period there was discrepancy between facial palsy score of clinical signs and degree of nerve impairment by evoked myogram. On his 12th hospital day his facial nerve score improved 9 to 12 (0 complete paralysis, 40 no paralysis) but evoked myogram showed further progress of nerve impairment from 86% to 91% (Evoked wave heights were 14% and 9% of normal site respectively). The discrepancy is probably because facial palsy score reflects also neurapraxia of inflammatory nerve, and stellate ganglion block has no effect on changing course of facial nerve injury.

Aged↗
PubMed1990

[A complete relief of intractable postherpetic neuralgia with intrathecal methylprednisolone acetate].

A 72-year-old man, 154 cm tall, weighing 53 kg was suffering from severe herpetic neuralgia on his left 10th intercostal nerve area. His pain continued even he was treated with frequent epidural nerve block (4 to 5 times per week) by an anesthesiologist. He was referred to our hospital on his 105th pain day. He complained severe continuous pain and numbness on his left 10th intercostal nerve area. Touching the painful skin induced lightning pain. His pain was so severe that his sleeping was disturbed and also he could not maintain his usual life. Epidural nerve block at 10th thoracic nerve was done with 20mg methylprednisolone acetate and 5ml of 1% lidocaine. After the treatment, his pain was reduced to 3/10 of the one he had on admission, and also his sleep was not disturbed further. Epidural nerve blocks with methylprednisolone weekly for a month induced no more remission. At his 154th pain day, a dose of 20mg methyl prednisolone acetate and 1% lidocaine 5ml was given intrathecally through 2nd lumber intervertebral space. The pain was relieved completely after the block. And he complained nothing about the skin area which had been disturbing his life for a long time. Auditory brainstem response which was recorded during the block showed prolongation of the latency of phase III and phase V at 40 minutes after the intrathecal injection of lidocaine.

Aged↗
PubMed1984

Age-related changes in the Purkinje's cells in the rat cerebellar cortex: a quantitative electron microscopic study.

The present study was undertaken to assess age-related changes in the Purkinje's cells in the rat cerebellar cortex. The cellular and nucleolar volumes and the volume percentage of lipofuscin per cytoplasma were measured in six age groups. The number of Purkinje's cells was also counted. The cellular volume of rats aged 18, 24 and 30 months decreased significantly as compared with that of 3-month-old rats. The nucleolar volume of rats aged 12, 18, 24 and 30 months decreased significantly as compared with that of 3-month-old rats. The accumulation of lipofuscin in the cytoplasma of the Purkinje's cells was observed more or less in all ages. The degree of accumulation of lipofuscin in the Purkinje's cells increased with aging. The number of Purkinje's cells at the ages of 24 and 30 months decreased significantly as compared with that of 3-month-old rats.

Aging↗
PubMed1983

Evaluation and management in consultation-liaison psychiatry.

The subjects were 95 medical and surgical inpatients referred to Kyushu University Hospital Psychiatric Consultation Service. The authors studied the mental status of each referred patient and elicited some Unclassified mental status cases. It was recommended, therefore, to bring in new concepts of normal condition and polymorphous condition in dealing with those Unclassified mental status cases which are often recognized as problematic both by the patient's primary physician and the psychiatric consultant. The ordinary style Single contact consultation was also compared with the Active follow-up consultation regarding the function of psychiatric consultations. The authors confirmed that most referring physicians who were supported by the Active follow-up consultation appreciated highly the evaluating function of a psychiatric consultant.

Adolescent↗
PubMed1982

Age-related changes in the neuropil in the rat inferior olive nucleus: quantitative electron microscopic study.

Age-related ultrastructural changes in the neuropil in the rat inferior olive nucleus were examined at 3, 6, 12, 18, 24 and 30 months old. The profiles of axon terminals, dendrites and astroglial processes from random samplings within the neuropil were traced. Subsequently, the percentages of these profiled areas in relation to the area of neuropil (relative volume fraction) were examined using the image analyzer system. The relative volume fractions of both axon terminals and dendrites in relation to the neuropil were found to have decreased in the aged rats, while the relative volume fraction of astroglial processes had progressively increased with aging.

Aging↗
PubMed1982

Psychiatric consultations at medical and surgical wards: the role of psychiatric consultant.

A one-year survey was conducted on the psychiatric consultation work at Kyushu University Hospital. It was found that an organic brain syndrome was the most frequent psychiatric diagnosis of the referred patients. The most frequent purpose of request for psychiatric consultations was for the management of the patient. The main consultant functions were diagnoses and to advise on the management of the patient. The consultant functions agreed with the purposes of request in many cases, but discrepancies between the two were found about the patient disposition. The nature of the consultant role was compared with some American studies. It was deemed necessary that consultation-liaison psychiatry based on Japan's present conditions, medical and social, should be developed.

Humans↗
PubMed1982

Terminal degeneration in the lateral septum of the rat after suprachiasmatic nucleus lesion.

Nerve terminals in the lateral septum were studied by electron microscopy in the rat after lesions of the suprachiasmatic nuclei (SCN). The results were as follows: 1) The electron-lucent degenerations showed a reduction in the number of vesicles and the swelling of terminals and/or vesicles. These degenerating terminals predominated at two days of survival period. The electron-dense degenerations which showed a darkening and shrinkage of the terminals mainly appeared at four days of survival period. 2) Most of the degenerating terminals contained large core vesicles of a diameter in the range of 800-1500 A. 3) The percentage of the degenerating terminals to all the terminals on the electron micrographs was about 7%. 4) The F-type synapses were not found in the lateral septum of the normal and SCN lesion rats. These data confirmed the existence of the projection which reached the lateral septum from the SCN and suggested to us that these synapses were so-called peptidergic synapses.

Animals↗