Research Achievements - Original paper -
-
Comparative Study of Transcriptome in the Hearts Isolated from Mice, Rats, and Humans
Okada D.
Biomolecules ( Biomolecules ) 12 ( 6 ) 2022.06 [Refereed]
Research paper (journal)
-
Okamoto Y.
Biomolecules ( Biomolecules ) 12 ( 5 ) 2022.05 [Refereed]
Research paper (journal)
-
Nomura K.
Environmental Health and Preventive Medicine ( Environmental Health and Preventive Medicine ) 26 ( 1 ) 2021.12 [Refereed]
Research paper (journal)
-
Fukuda Y.
Biology of Reproduction ( Biology of Reproduction ) 105 ( 1 ) 258 - 266 2021.07 [Refereed]
Research paper (journal)
<jats:title>Abstract</jats:title>
<jats:p>To cryopreserve cells, it is essential to avoid intracellular ice formation during cooling and warming. One way to achieve this is to convert the water inside the cells into a non-crystalline glass. It is currently believed that to accomplish this vitrification, the cells must be suspended in a very high concentration (20–40%) of a glass-inducing solute, and subsequently cooled very rapidly. Herein, we report that this belief is erroneous with respect to the vitrification of one-cell rat embryos. In the present study, one-cell rat embryos were vitrified with 5 μL of EFS10 (a mixture of 10% ethylene glycol (EG), 27% Ficoll, and 0.45 M sucrose) in cryotubes at a moderate cooling rate, and warmed at various rates. Survival was assessed according to the ability of the cells to develop into blastocysts and to develop to term. When embryos were vitrified at a 2613 °C/min cooling rate and thawed by adding 1 mL of sucrose solution (0.3 M, 50 °C) at a warming rate of 18 467 °C/min, 58.1 ± 3.5% of the EFS10-vitrified embryos developed into blastocysts, and 50.0 ± 4.7% developed to term. These rates were similar to those of non-treated intact embryos. Using a conventional cryotube, we achieved developmental capabilities in one-cell rat embryos by rapid warming that were comparable to those of intact embryos, even using low concentrations (10%) of cell-permeating cryoprotectant and at low cooling rates.</jats:p> -
Takahashi K.
Heliyon ( Heliyon ) 7 ( 6 ) 2021.06 [Refereed]
Research paper (journal)
-
Requirement of the Ca<sup>2+</sup> channel β<inf>2</inf> subunit for sympathetic PKA phosphorylation
Murakami M.
Journal of Pharmacological Sciences ( Journal of Pharmacological Sciences ) 145 ( 3 ) 253 - 261 2021.03 [Refereed]
Research paper (journal)
-
Detection of pathologic heart murmurs using a piezoelectric sensor
Takahashi K.
Sensors (Switzerland) ( Sensors (Switzerland) ) 21 ( 4 ) 1 - 12 2021.02 [Refereed]
Research paper (journal)
-
Takagi D.
Journal of Physiological Sciences ( Journal of Physiological Sciences ) 70 ( 1 ) 2020.02 [Refereed]
Research paper (journal)
-
Okamoto Y.
Journal of Biological Chemistry ( Journal of Biological Chemistry ) 294 ( 44 ) 16049 - 16061 2019.11 [Refereed]
Research paper (journal)
-
Umehara S.
International Journal of Molecular Sciences ( International Journal of Molecular Sciences ) 20 ( 12 ) 2019.06 [Refereed]
Research paper (journal)
-
Medaka as a model for ECG analysis and the effect of verapamil
Yonekura M.
Journal of Pharmacological Sciences ( Journal of Pharmacological Sciences ) 137 ( 1 ) 55 - 60 2018.05 [Refereed]
Research paper (journal)
-
Stromal interaction molecule 1 haploinsufficiency causes maladaptive response to pressure overload
Ohba T.
PLoS ONE ( PLoS ONE ) 12 ( 11 ) 2017.11 [Refereed]
Research paper (journal)
-
In vitro effect of nicorandil on the carbachol-induced contraction of the lower esophageal sphincter of the rat.
Tomonori Shimbo, Takeshi Adachi, Susumu Fujisawa, Mai Hongoh, Takayoshi Ohba, Kyoichi Ono
Journal of pharmacological sciences 131 ( 4 ) 267 - 74 2016.08 [Refereed]
Research paper (journal)
The lower esophageal sphincter (LES) is a specialized region of the esophageal smooth muscle that allows the passage of a swallowed bolus into the stomach. Nitric oxide (NO) plays a major role in LES relaxation. Nicorandil possesses dual properties of a NO donor and an ATP-sensitive potassium channel (KATP channel) agonist, and is expected to reduce LES tone. This study investigated the mechanisms underlying the effects of nicorandil on the LES. Rat LES tissues were placed in an organ bath, and activities were recorded using an isometric force transducer. Carbachol-induced LES contraction was significantly inhibited by KATP channel agonists in a concentration-dependent manner; pinacidil >> nicorandil ≈ diazoxide. Nicorandil-induced relaxation of the LES was prevented by pretreatment with glibenclamide, whereas N(G)-nitro-l-arginine methyl ester (l-NAME), 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) and iberiotoxin were ineffective at preventing nicorandil-induced LES relaxation. Furthermore, nicorandil did not affect high K(+)-induced LES contraction. Reverse-transcription polymerase chain reaction analysis and immunohistochemistry revealed expression of KCNJ8 (Kir6.1), KCNJ11 (Kir6.2), ABCC8 (SUR1) and ABCC9 (SUR2) subunits of the KATP channel in the rat lower esophagus. These findings indicate that nicorandil causes LES relaxation chiefly by activating the KATP channel, and that it may provide an additional pharmacological tool for the treatment of spastic esophageal motility disorders.
-
Age-related effects of dexmedetomidine on myocardial contraction and coronary circulation in isolated guinea pig hearts.
Maiko Hongo, Susumu Fujisawa, Takeshi Adachi, Tomonori Shimbo, Shigehiro Shibata, Takayoshi Ohba, Kyoichi Ono
Journal of pharmacological sciences 131 ( 2 ) 118 - 25 2016.06 [Refereed]
Research paper (journal)
Dexmedetomidine is a selective α2 adrenergic agonist. Although dexmedetomidine is widely used for sedation and analgesia, it frequently produces hypotension and bradycardia. The present study aimed to evaluate the effects of dexmedetomidine on cardiac function and coronary circulation using Langendorff-perfused guinea pig hearts. Coronary perfusion pressure (CPP) and left ventricular pressure (LVP) were continuously monitored, and electric field stimulation (EFS) was applied to stimulate sympathetic nerve terminals. Dexmedetomidine almost completely inhibited the EFS-induced increase in LVP at all ages. The effect of dexmedetomidine on coronary artery resistance varied according to postnatal age, i.e., dexmedetomidine had little effect on CPP in young hearts (<4 weeks) but increased CPP by 10 mmHg at 4-8 weeks and by 15 mmHg at >8 weeks. The increase in CPP in adult hearts was inhibited by imiloxan, an α2B antagonist, and prazosin, an α1 antagonist. The results suggest that dexmedetomidine acts on α2 adrenergic receptors at sympathetic nerve terminals to suppress the release of norepinephrine. In addition, the findings suggest that dexmedetomidine directly affects α1 adrenoceptors and/or α2B adrenoceptors on coronary smooth muscles to increase CPP. The age-related changes in α adrenoceptor subtypes may be linked to the cardiodepressant effects of dexmedetomidine.
-
Modified sympathetic nerve regulation in AKAP5-null mice.
Chong Han, Hirofumi Tomita, Takayoshi Ohba, Kimitaka Nishizaki, Yoshiki Ogata, Yasushi Matsuzaki, Daisuke Sawamura, Teruyuki Yanagisawa, Tomohiro Osanai, Tadaatsu Imaizumi, Atsushi Matsubara, Takeshi Adachi, Kyoichi Ono, Ken Okumura, Manabu Murakami
Biochemical and biophysical research communications 469 ( 4 ) 897 - 902 2016.01 [Refereed]
Research paper (journal)
Genetic analyses have revealed an important association between A-kinase anchoring proteins (AKAPs) and the intracellular calcium modulating system. AKAP5, also known as AKAP79/150, is an anchoring protein between PKA and voltage-dependent calcium channels, ryanodine receptor-2, phospholamban and other molecules. The aim of the present study was to elucidate the physiological importance of AKAP5 in the creation of cardiac rhythm using AKAP5-null mice. ECG analysis showed a normal sinus rhythm and a decreased responsiveness to isoproterenol in AKAP5-null mice compared with wild-type mice. Analysis of heart rate variability revealed that the R-R interval was unstable in AKAP5-null mutants and that the low-frequency components had decreased, indicating that the tonus of the sympathetic nervous system was affected. Furthermore, the atrium of the AKAP5-null mice showed a decreased positive inotropic response to isoproterenol, indicating the involvement of AKAP5 in a PKA-dependent pathway. Thus, our present study revealed that AKAP5 plays a significant role in the regulation of sympathetic nerve activities.
-
Involvement of the orexin system in sympathetic nerve regulation.
Manabu Murakami, Takayoshi Ohba, Testuya Kushikata, Hidetoshi Niwa, Akira Kurose, Tadaatsu Imaizumi, Hiroyuki Watanabe, Teruyuki Yanagisawa, Shigeyuki Nakaji, Kyoichi Ono, Kazuyoshi Hirota
Biochemical and biophysical research communications 460 ( 4 ) 1076 - 81 2015.05 [Refereed]
Research paper (journal)
Orexin, also known as hypocretin, is a secreted neuropeptide implicated in the regulation of sleep and food intake. In the present study, we examined the importance of orexin in regulation of the sympathetic nervous system using an orexin/ataxin-3 transgenic (OXTg) rat, which has a minimal number of orexin neurons. RT-PCR analysis identified expression of prepro-orexin and orexin receptor-1 (OX1R) in the superior cervical ganglion (SCG), and expression of another receptor (OX2R) was marginal in the wild-type rat. The orexin/ataxin-3 transgenic rat showed increased expression of OX1R and OX2R, whereas expression of prepro-orexin was undetectable, suggesting a compensatory increase in both receptors. In the ECG recording (R-R interval), orexin/ataxin-3 transgenic rats showed decreased responsiveness to the β-adrenergic blocker propranolol. Furthermore, OXTg rats had deteriorated R-R interval regulation, indicating involvement of the orexin system in sympathetic nerve regulation. This was accompanied by decreased baroreflex and responsiveness to β-adrenergic blocker in blood pressure recording, also suggesting involvement of the orexin system in sympathetic nerve regulation. Histological examination revealed hypotrophic changes in the transgenic heart, suggesting involvement of the orexin system in cardiac development. Taken together, our present results indicate involvement of the orexin system in sympathetic nerve control.
-
Modified autonomic regulation in mice mutated in the β4 subunit of the lh/lh calcium channel.
Manabu Murakami, Takashi Suzuki, Tsai-Wen Wu, Kenji Kuwasako, Eiki Takahashi, Hiroyuki Watanabe, Agnieszka M Murakami, Ichiro Miyoshi, Teruyuki Yanagisawa, Hironobu Sasano, Kyoichi Ono, Takayoshi Ohba
Biochemical and biophysical research communications 461 ( 2 ) 200 - 5 2015.05 [Refereed]
Research paper (journal)
Genetic analyses have revealed an important association between P/Q-type calcium channel activities and hereditary neurological disorders. The P/Q-type channels are composed principally of heterologous multimeric subunits including CaV2.1 and CaVβ4. Of these, the β4 subunit is thought to play a significant role in channel physiology, because a mouse line mutant in that subunit (the lethargic mouse: lh) exhibits a severe ataxic phenotype. The aim of the present study was to elucidate the physiological importance of the β4 subunit. ECG analysis showed that the T wave was high in 8-week-old lh mutants; this may be associated with hyperkalemia. Upon pharmacological ECG analysis, 2-3-week-old lh mutants exhibited reduced responses to a β-blocker and a muscarinic receptor antagonist. Analysis of heart rate variability revealed that the R-R interval was unstable in lh mutants and that both the low- and high-frequency components had increased in extent, indicating that the tonus of both the sympathetic and parasympathetic nervous systems was modified. Thus, our present study revealed that the β4 subunit played a significant role in regulation of sympathetic and parasympathetic nerve activities.
-
Apnea during Cheyne-Stokes-like breathing detected by a piezoelectric sensor for screening of sleep disordered breathing
Takashi Koyama, Shinichi Sato, Takashi Kanbayashi, Hideaki Kondo, Hiroyuki Watanabe, Seiji Nishino, Tetsuo Shimizu, Hiroshi Ito, Kyoichi Ono
SLEEP AND BIOLOGICAL RHYTHMS ( WILEY-BLACKWELL ) 13 ( 1 ) 57 - 67 2015.01 [Refereed]
Research paper (journal)
A simplified diagnostic/monitoring instrument for use in primary screening for sleep-disordered breathing (SDB) has been desired. This study was designed to assess the validity of a newly developed piezoelectric sensor as a simple and noninvasive tool for primary screening for sleep-disordered breathing. Forty-three consecutive patients suspected of having sleep-disordered breathing and 10 healthy volunteers were enrolled. Breathing movement was detected with the piezoelectric sensor (180 x 30 x 1mm), which was placed under a bed sheet under patients, and simultaneous polysomnographic recordings were obtained. We counted the number of apneas of >10s, irrespective of central or obstructive, that appeared during Cheyne-Stokes-like breathing with a waxing and waning pattern with an amplitude ratio of >10 in the piezoelectric sensor signal. The correlation coefficient between the number of apneas and apnea-hypopnea index (AHI) was 0.74 (P < 0.0001). The sensitivity/specificity of the number of apneas for distinguishing non-SDB patients from mild SDB patients (AHI 5) were 92.1/60.0% and those for separating moderate to severe (AHI 15) and severe (AHI 30) SDB patients from the other patients were 96.9/100% and 93.8/86.5%, respectively. There were no complaints from patients about the use of the piezoelectric sensor. The results indicate that the number of apneas detected by this piezoelectric sensor during Cheyne-Stokes-like breathing is a potential new index for primary screening for SDB at least for cardiac patients. Thus, the piezoelectric-sensor system might be useful for simple, noninvasive and comfortable SDB screening at home, hospitals and health care facilities.
-
Pathological impact of hyperpolarization-activated chloride current peculiar to rat pulmonary vein cardiomyocytes.
Yosuke Okamoto, Koichi Kawamura, Yuta Nakamura, Kyoichi Ono
Journal of molecular and cellular cardiology 66 53 - 62 2014.01 [Refereed]
Research paper (journal)
Pulmonary veins (PVs) are believed to be a crucial origin of atrial fibrillation. We recently reported that rat PV cardiomyocytes exhibit arrhythmogenic automaticity in response to norepinephrine. Herein, we further characterized the electrophysiological properties underlying the potential arrhythmogenicity of PV cardiomyocytes. Patch clamping studies revealed a time dependent hyperpolarization-activated inward current in rat PV cardiomyocytes, but not in left atrial (LA) myocytes. The current was Cs(+) resistant, and was not affected by removal of external Na(+) or K(+). The current was inhibited with Cd(2+), and the reversal potential was sensitive to changes in [Cl(-)] on either side of the membrane in a manner consistent with a Cl(-) selective channel. Cl(-) channel blockers attenuated the current, and slowed or completely inhibited the norepinephrine-induced automaticity. The biophysical properties of the hyperpolarization-activated Cl(-) current in rat PVs were different from those of ClC-2 currents previously reported: (i) the voltage-dependent activation of the Cl(-) current in rat PVs was shifted to negative potentials as [Cl(-)]i increased, (ii) the Cl(-) current was enhanced by extracellular acidification, and (iii) extracellular hyper-osmotic stress increased the current, whereas hypo-osmotic cell swelling suppressed the current. qPCR analysis revealed negligible ClC-2 mRNA expression in the rat PV. These findings suggest that rat PV cardiomyocytes possess a peculiar voltage-dependent Cl(-) channel, and that the channel may play a functional role in norepinephrine-induced automaticity.
-
Effects of propofol on electrocardiogram measures in mice.
Tomohiro Shintaku, Takayoshi Ohba, Hidetoshi Niwa, Tetsuya Kushikata, Kazuyoshi Hirota, Kyoichi Ono, Yasushi Matsuzaki, Tadaatsu Imaizumi, Kenji Kuwasako, Daisuke Sawamura, Manabu Murakami
Journal of pharmacological sciences 126 ( 4 ) 351 - 8 2014 [Refereed]
Research paper (journal)
We investigated the anesthetic effects of propofol on the electrocardiogram (ECG) in mice. We also compared the effects of isoflurane (2%) inhalation anesthesia, intraperitoneal propofol (50 or 100 mg/kg), and pentobarbital (50 mg/kg) on ECG in mice. Isoflurane inhalation and pentobarbital anesthesia were both associated with an acceptable heart rate (HR) range (ca. 450 - 500 bpm). In contrast, high-dose propofol anesthesia significantly decreased the HR. Importantly, propofol anesthesia led to significantly reduced responses to propranolol, a β-blocker, suggesting that it affects sympathetic tonus and is not suitable for the evaluation of cardiovascular or sympathetic function. Propofol also reduced the response to atropine, indicative of suppression of mouse parasympathetic nerve activity. Our data suggest that propofol anesthesia should not be the first choice for cardiovascular analysis in mice.