A5002507108- Cardiac electrophysiology and arrhythmias
- Ion channel regulation and function
- Neuroscience and Neural Engineering
- Neuroscience and Neuropharmacology Research
- Pain Mechanisms and Treatments
- Nitric Oxide and Endothelin Effects
- Cardiovascular Function and Risk Factors
- Receptor Mechanisms and Signaling
- Adipose Tissue and Metabolism
- Cardiomyopathy and Myosin Studies
- Musculoskeletal pain and rehabilitation
- Cardiac Ischemia and Reperfusion
- Heart Rate Variability and Autonomic Control
- Electrochemical Analysis and Applications
- Mitochondrial Function and Pathology
- Cardiovascular and exercise physiology
- Myofascial pain diagnosis and treatment
- Osteoarthritis Treatment and Mechanisms
- Ion Transport and Channel Regulation
- Renin-Angiotensin System Studies
- Congenital heart defects research
- Heart Failure Treatment and Management
- Caveolin-1 and cellular processes
- Neutrophil, Myeloperoxidase and Oxidative Mechanisms
- Ion Channels and Receptors
Sapporo Medical University
2013-2024
Sapporo University
2006-2008
Hokkaido University
1988-1998
Chiba University
1994
University of Cincinnati Medical Center
1990-1993
University of Cincinnati
1992
National Institute for Physiological Sciences
1987-1990
The calcium sensitivity of the delayed rectifier K+ current (IK) was investigated in guinea pig single ventricular cells using whole cell configuration patch-clamp technique with a dialysis method. concentration-response curve IK for intracellular Ca2+ indicated that started to increase at concentration [Ca2+]i 10(-8) M (pCa 8) and it increased threefold pCa 7. At lower than 9, remained unchanged. A shift activation by elevation not observed. Although had little effect on time constants...
Effects of protein kinase C (PKC) and intracellular calcium ion (Cai2+) on the delayed rectifier K+ current (IK) were investigated in single ventricular cells guinea pig by use an internal-dialysis method a whole cell voltage-clamp technique. 12-O-tetradecanoylphorbol-13-acetate (TPA, 10(-9) M), activator PKC, increased amplitude IK presence Cai2+ higher than 10(-10) M. This effect TPA was mimicked synthetic diacylglycerol, 1-oleoyl-2-acetylglycerol (OAG), 50 micrograms/ml, 125 microM,...
Electrophysiological effects of MS‐551, a new class III antiarrhythmic drug, were examined and compared with those (+)‐sotalol in rabbit ventricular cells. In muscles stimulated at 1.0 Hz, MS‐551 (0.1–10 μ m ) (3–100 prolonged action potential duration (APD) effective refractory period without affecting the maximum upstroke velocity phase 0 depolarization . The effect was approximately 30 times more potent than that (+)‐sotalol. Class showed reverse use‐dependence, i.e., greater prolongation...
Effects of atrial natriuretic peptide (ANP) on the L‐type Ca 2+ channels were examined in rabbit isolated ventricular cells by use whole‐cell and cell‐attached configurations patch clamp methods. ANP produced a concentration‐dependent decrease (10–100 n m ) amplitude basal channel current. The inactive (methionine‐oxidized ANP, 30 failed to 8‐Bromo‐cyclic GMP (300 μ ), potent activator cyclic GMP‐dependent protein kinase (PKG), same effects current as those ANP. GMP‐induced inhibition was...
Effects of cGMP on the slow (L-type) Ca2+ channels cultured chick embryonic cardiomyocytes were investigated by a cell-attached patch-clamp method. Superfusion single cells with 8-bromo-cGMP, membrane-permeable derivative cGMP, inhibited single-channel activity. The cyclic nucleotide decreased, in concentration-dependent manner, ensemble averaged currents obtained from multichannel patches. 8-Bromo-cGMP (1 mM) completely abolished (n = 8), whereas 0.1 mM only slightly decreased 4). influence...
In order to determine whether activation of adenosine triphosphate (ATP)‐sensitive K + channels exclusively explains the hypoxia‐ and ischaemia‐induced action potential shortening, effects tolbutamide glibenclamide on changes in duration (APD) during hypoxia, metabolic blockade or experimental ischaemia were examined guinea‐pig canine isolated myocardium by standard microelectrode techniques. With use patch clamp techniques, activity ATP‐sensitive was recorded from open cell‐attached patches...
Humoral immunity is vital for host protection, yet aberrant antibody responses can trigger harmful inflammation and immune-related disorders. T follicular helper (Tfh) cells, central to humoral immunity, have garnered significant attention unraveling immune mechanisms. This study shows the role of B-cell Oct-binding protein 1 (Bob1), a transcriptional coactivator, in Tfh cell regulation. Our investigation, utilizing conditional Bob1-deficient mice, suggests that Bob1 plays critical...
Mutations in a human cardiac Na+ channel gene (SCN5A) are responsible for chromosome 3-linked congenital long QT syndrome (LQT3). Here we characterized de novo missense mutation (R1623Q, S4 segment of domain 4) identified an infant Japanese girl with severe form LQT3. When expressed oocytes, mutant channels exhibited only minor abnormalities activation, but contrast to three previously LQT3 mutations, had significantly delayed macroscopic inactivation. Single analysis revealed that R1623Q...
The effect of alpha 1-adrenoceptor stimulation on the delayed rectifier K+ current (IK) was examined in isolated guinea pig ventricular cells by use patch-clamp method. IK evoked a 3-second depolarizing pulse from holding potential -30 mV Na(+)- and K(+)-free solution containing 3 microM nifedipine. Phenylephrine (30 microM) presence propranolol (1 produced an increase IK. In five cells, phenylephrine increased tail 23 +/- 5%. This blocked prazosin (0.3 microM), selective 1-blocker. only...
Recently it has been postulated that oxygen-derived free radicals may be involved in reperfusion-induced arrhythmias. This study was undertaken to evaluate cellular electrophysiological alterations produced by peroxidation of membrane lipids isolated cardiac tissues. In retrogradely perfused guinea pig hearts, perfusion organic hydroperoxides, cumene hydroperoxide (CH), and tert-butyl (TBH) caused conduction disturbances arrhythmias, concomitantly with an increase malondialdehyde (MDA)...
Abstract The initiation of heartbeat is an essential step in cardiogenesis the heart primordium, but it remains unclear how intracellular metabolism responds to increased energy demands after initiation. In this study, embryos Wistar rats at embryonic day 10, which begins rats, were divided into two groups by primordium before and their metabolic characteristics assessed. Metabolome analysis revealed that levels ATP, a main product glucose catabolism, reduced glutathione, by-product pentose...
Gating properties of Na(+) channels are the critical determinants for state-dependent block by class I antiarrhythmic drugs; however, recent site-directed mutagenesis studies have shown that channel selectivity filter region controls drug access to and dissociation from binding site. To validate these observations, we exploited a naturally occurring cardiac mutation, S1710L, located next putative residue domain 4, evaluated pharmacological mexiletine using whole-cell, patch-clamp recordings....
Abstract To evaluate the preventive effect of regression left ventricular hypertrophy (LVH) on sudden cardiac death (SCD), incidence tachycardia or fibrillation (VT/Vf) after coronary artery occlusion in Langendorff preparations was studied following five groups: (1) spontaneously hypertensive rats (SHR) without treatment (SHR-N), (2) SHR treated with captopril (SHR-C), (3) angiotensin II receptor antagonist TCV-116 (SHR-A), (4) hydralazine (SHR-H), and (5) Wistar-Kyoto (WKY) rats. Although...
In the early (3-day) stage of development, long-lasting openings L-type Ca2+ channels (mode 2) occur in embryonic chick heart cells. Since mode-2 behavior is infrequently observed adult cells other species, present study, developmental change channel was examined young and old (17-day) whole-cell voltage clamp, current carried by ions smaller amplitude had a faster inactivation 17-day than 3-day The peak density 8.1 +/- 0.2 microA/cm2 (mean SEM, n = 5) 5.1 0.3 (n cells, respectively. When...
In Brief Study Design. The DRG neuron was electrophysiologically investigated using a rat model with constriction of the proximal site DRG. Objectives. To investigate pathomechanisms lumbar radiculopathy, we established And to characterize neurons in physiologic properties regarding action potential, Na+, and K+ current were analyzed through use patch clamp recordings. Summary Background Data. root models, secondary afferent dorsal horn have been investigated. However, electrical not well...
In the present study, we examined if and how cardiac ion channels are modified by type 2 diabetes mellitus (T2DM). Subendocardial (Endo) myocytes subepicardial (Epi) were isolated from left ventricles of Otsuka-Long-Evans-Tokushima Fatty rats (OLETF) rats, a rat model T2DM, (LETO) (nondiabetic control rats). Endo Epi used for whole cell patch-clamp recordings protein mRNA analyses. Action potential durations in longer OLETF than LETO difference was larger myocytes. Steady-state transient...
Background: Lumbar radicular pain is categorized as a type of neuropathic pain, but its pathophysiological mechanisms are not fully understood. The substantia gelatinosa (SG) in the spinal cord dorsal horn receives primary afferent inputs and considered to be therapeutic target for treating pain. In vivo patch-clamp recording useful procedure analyzing functional properties synaptic transmission SG neurons. Transient receptor potential ankyrin 1 (TRPA1) has been widely identified central...
1. Single cardiomyocytes of 18‐day‐old rat fetuses were isolated to characterize the cardiac Ca2+ channels in fetal period, using whole‐cell voltage clamp (Na+, K(+)‐free external solution and internal solution), depolarizing test pulses from a holding potential (HP) ‐87 mV applied. 2. The current was completely blocked by 2 mM‐CO2+, but not dihydropyridine (DHP) antagonist nifedipine. Nifedipine (3 microM) decreased amplitude (at ‐7 mV) 65.9 +/‐ 3.4% (n = 20). At HP ‐47 mV, nifedipine about...