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論文
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Nozaki, Shuhei ; Ogata, Yoshiki ; Yonekura, Manabu ; Han, Chong ; Niwa, Hidetoshi ; Kushikata, Tetsuya ; Hirota, Kazuyoshi ; Matsuzaki, Yasushi ; Tomita, Hirofumi ; Imaizumi, Tadaatsu ; Itagaki, Shirou ; Sawamura, Daisuke ; Murakami, Manabu
概要:
We analyzed the effects of halothane as an inhalational anesthetic agent on electrocardiogram （ECG）parameters in C57/BL6
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mice. Following induction of anesthesia using 2% halothane, the ECGs showed a regularpattern and the heart rate （HR） was within an acceptable range （~500 bpm）. The HR decreased with increasinghalothane concentration in a concentration-dependent fashion. The frequency domain analysis showed that the high-frequency （HF） component decreased and the lowfrequency（LF） component increased in a concentration-dependent fashion. Therefore, the LF/HF ratio increasedwith increasing halothane concentration, suggesting effects on the autonomic nervous system. We analyzed the pharmacological response to sympathetic blockade with propranolol, a typical adrenergicβ-blocker, under halothane anesthesia. Propranolol administration resulted in a decreased HR; interestingly,intraperitoneal injection of propranolol （120 μg/kg body weight） resulted in arrhythmia （sick sinus syndrome）during anesthesia with 3% halothane. Our results indicate the importance of selecting a suitable anesthetic agent for C57/BL6 mice in pharmacological studies
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| 2.
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Ogata, Yoshiki ; Yonekura, Manabu ; Yamaki, Rouichi ; Han, Chong ; Fujiwara, Tomonori ; Seya, Kazuhiko ; Niwa, Hidetoshi ; Kushikata, Tetsuya ; Imaizumi, Tadaatsu ; Hirota, Kazuyoshi ; Tomita, Hirofumi ; Murakami, Manabu
概要:
We examined the effects of enflurane anesthesia on the mouse cardiac autonomic nervous system usingelectrocardiogram（ EC
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G） analysis. Enflurane had a lower effect on heart rate（ HR） compared to isoflurane, which ismore widely used in small animal studies. Under anesthesia with 3 or 4% of enflurane, administration of propranololhad a significant effect on HR. Enflurane increased R-R interval length in a dose-dependent fashion, and the R-Rinterval became unstable at high concentrations. Although HR decreased with high doses of enflurane, we observednormal sinus rhythm and no arrhythmia. These results suggest that the effect of enflurane anesthesia is acceptableeven though the drug can lead to cardiac instability. No remarkable changes were observed in HR frequency. These results suggest that enflurane anesthesia may be suitable for cardiac autonomic nervous system analysis.
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| 3.
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Han, Chong ; Inaba, Wataru ; Yonekura, Manabu ; Ogata, Yoshiki ; Ohba, Takayoshi ; Kushikata, Tetsuya ; Niwa, Hidetoshi ; Yanagisawa, Teruyuki ; Tomita, Hirofumi ; Itagaki, Shirou ; Hirota, Kazuyoshi ; Akai, Hiroaki ; Mizukami, Hiroki ; Murakami, Manabu
概要:
Persistent hyperglycemia is implicated in the pathogenesis of chronic diabetic complications, such asneuropathy. Theref
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ore, we investigated Electrocardiogram（ ECG）-related changes, including various ECG parametersand heart rate variability, and neuropathic changes in diabetic Goto-Kakizaki （GK） rats, a spontaneous model fortype 2 diabetes. GK rats （50 weeks old） showed increased plasma glucose and decreased R-R interval variability,which was likely due to diabetic polyneuropathy in the autonomic nervous system. Interestingly, GK rats showed adecreased baroreflex compared with control Wistar rats. Furthermore, GK rats showed limited fluctuation changesin beat-to-beat dynamics. In the frequency domain analysis, the low-frequency component was similar but the highfrequencycomponent was significantly decreased in GK rats, suggesting decreased parasympathetic nerve regulationand conserved sympathetic nerve regulation. In addition, GK rats showed a limited response to high-dose atropine, amuscarinic receptor antagonist, indicating modified parasympathetic nerve regulation in GK rats. Our data stronglysuggests that GK rat could be a nice animal model for chronic cardiovascular disease related to diabetic neuropathy.
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| 4.
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論文
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Toyama, Yuichi ; Yonekura, Manabu ; Arakawa, Yoshiaki ; Higuchi, Shoki ; Tomita, Hirofumi ; Murakami, Agnieszka ; Itagaki, Shirou ; Murakami, Manabu
概要:
The cardiac action potential in the sinoatrial node is important, as it propagates throughout the heart and determines cardiac rhythm. Because of the anatomical complexity, pacemaker cells in the sinoatrial node can be difficult
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to identify for ectrophysiological analysis. Also, analysis of pacemaker cells requires a specialized technique. In this study, we tried to analyze pacemaking in the sinoatrial node. First, we evaluated the expression of various factors that participate in pacemaking or modify cardiac rhythm. Next, we evaluated recordings of the action potential in the sinoatrial node by a conventional lectrophysiological technique and using oxonol V, a fluorescent voltage-sensitive dye.
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Niisawa, Tomoyuki ; Naruta, Naoki ; Murakami, Agnieszka M ; Yonekura, Manabu ; Hirota, Kazuyoshi ; Itagaki, Shirou ; Murakami, Manabu
概要:
Orexin （hypocretin） is a neuropeptide secreted by hypothalamic neurons that is activated duringmotivating behaviors and
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active waking. Our knowledge of orexin is mainly limited to mammalian species, such ashumans, mice, and rats. In the present study, we cloned orexin and its receptor from the medaka brain. Additionally,we analyzed the effect of an orexin inhibitor （SB-649868） on spontaneous behavior. The orexin inhibitor decreasedresults indicate that medaka might be a suitable animal model for neurological behavioral studies.
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