The Japanese Journal of Physiology
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Volume 54, Issue 5
Displaying 1-9 of 9 articles from this issue
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Review
  • Cardiovascular Modules in the Cerebellum
    Naoko Nisimaru
    2004 Volume 54 Issue 5 Pages 431-448
    Published: 2004
    Released on J-STAGE: January 29, 2005
    DOIhttps://doi.org/10.2170/jjphysiol.54.431
    JOURNAL FREE ACCESS
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    Mapping with local lesions, electrical or chemical stimulation, or recording evoked field potentials or unit spikes revealed localized representations of cardiovascular functions in the cerebellum. In this review, which is based on literatures in the field (including our own publications), I propose that the cerebellum contains five distinct modules (cerebellar corticonuclear microcomplexes) dedicated to cardiovascular control. First, a discrete rostral portion of the fastigial nucleus and the overlying medial portion of the anterior vermis (lobules I, II and III) conjointly form a module that controls the baroreflex. Second, anterior vermis also forms a microcomplex with the parabrachial nucleus. Third, a discrete caudal portion of the fastigial nucleus and the overlying medial portion of the posterior vermis (lobules VII and VIII) form another module controlling the vestibulosympathetic reflex. Fourth, the medial portion of the uvula may form a module with the nucleus tractus solitarius and parabrachial nucleus. Fifth, the lateral edge of the nodulus and the uvula, together with the parabrachial nucleus and vestibular nuclei, forms a cardiovascular microcomplex that controls the magnitude and/or timing of sympathetic nerve responses and stability of the mean arterial blood pressure during changes of head position and body posture. The lateral nodulus-uvula appears to be an integrative cardiovascular control center involving both the baroreflex and the vestibulosympathetic reflex.
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Regular Papers
  • Endogenous Cryogens Existing in the Blood of a Hypothermic Patient
    Osamu Shido, Naotoshi Sugimoto, Toshiaki Imoto, Akira Asai, Megumi Mar ...
    2004 Volume 54 Issue 5 Pages 449-456
    Published: 2004
    Released on J-STAGE: January 29, 2005
    DOIhttps://doi.org/10.2170/jjphysiol.54.449
    JOURNAL FREE ACCESS
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    We treated a young female patient who suffered from severe hypothermia. The etiology of the hypothermia was not identified, though various medical examinations were performed. Intraperitoneal (i.p.) injections of the patient's serum produced a significant and profound hypothermia in rats that was not associated with circulatory shock. The patient's serum was separated into 4 fractions by the use of various types of centrifugal filtration units according to molecular weights (MW), i.e., below 10 kDa, 10–30 kDa, 30–100 kDa, and beyond 100 kDa. The first two fractions never induced hypothermia in rats, but the i.p. injections of the fraction with MW from 30 to 100 kDa consistently produced hypothermia. The fraction with MW beyond 100 kDa caused marked hypothermia in one out of 3 rats tested. The results suggest that the patient was excessively producing endogenous cryogenic substances of which MW may be greater than 30 kDa.
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  • The Fetal Electrocardiogram by Independent Component Analysis and Wavelets
    Fumio Mochimaru, Yoshinobu Fujimoto, Yasuhiro Ishikawa
    2004 Volume 54 Issue 5 Pages 457-463
    Published: 2004
    Released on J-STAGE: January 29, 2005
    DOIhttps://doi.org/10.2170/jjphysiol.54.457
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    Once the fetal electrocardiogram (FECG) waveforms from ECG on the maternal abdomen are detected, the fetal P wave and T wave cannot always be identified by using continuous wavelet transform (CWT). We took noninvasive FECG from the maternal abdomen, extracted it from the maternal electrocardiogram waveforms after an Independent Component Analysis (ICA), and identified the features of those waveforms by using CWT. We also simultaneously analyzed the observed signals by Primary Component Analysis (PCA). FECG has been extracted by ICA from 25 of 30 pregnant women. The fetal P wave and T wave could be identified in 21 of the 25 cases. FECG was extracted by PCA in only one case. ICA is superior to PCA, whose separation quality highly depends on the careful positioning of the electrodes. We believe that after ICA, FECG obtained by the wavelet theory based method will become a powerful tool for the differential diagnosis of fetal arrhythmias.
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  • Breathing Patterns Associated with Trait Anxiety and Breathlessness in Humans
    Yuri Masaoka, Sandy Jack, Christopher J. Warburton, Ikuo Homma
    2004 Volume 54 Issue 5 Pages 465-470
    Published: 2004
    Released on J-STAGE: January 29, 2005
    DOIhttps://doi.org/10.2170/jjphysiol.54.465
    JOURNAL FREE ACCESS
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    Idiopathic hyperventilation (IH) is a condition of uncertain aetiology characterized by sustained arterial and alveolar hypocapnia and a plethora of symptoms, the most commonly reported being shortness of breath, and breathlessness. We previously reported that anxiety increases respiratory frequency and minute ventilation with no change in metabolism in normal subjects. In this study, we compared the breathing frequency response to 5% and 7% of CO2 gas mixtures in normal subjects (n = 13) and in subjects with IH (n = 9), taking into account anxiety and breathlessness in order to determine how breathing patterns may vary with changes in the degree of involvement of higher brain centers because of anxiety and the perception of breathlessness. CO2 produced a significantly higher value in respiratory frequency (f) in subjects with IH. Subjects with IH also showed lower PETCO2 than normal subjects. During the inhalation of room air, a significant correlation between f and trait anxiety scores was observed in normal subjects (r = 0.49) and IH subjects (r = 0.69). However, the IH group showed no significantly higher trait anxiety in comparison with normal subjects. There was a significant correlation between the level of perceived breathlessness and f during the inhalation of 5% and 7% CO2, even during the inhalation of room air in IH subjects. This study suggests that an excessive increase in f in subjects with IH may be due to the interaction of two factors, trait anxiety and breathlessness.
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  • Pressor Response to Static and Dynamic Knee Extensions at Equivalent Workload in Humans
    Satoshi Koba, Naoyuki Hayashi, Akira Miura, Masako Endo, Yoshiyuki Fuk ...
    2004 Volume 54 Issue 5 Pages 471-481
    Published: 2004
    Released on J-STAGE: January 29, 2005
    DOIhttps://doi.org/10.2170/jjphysiol.54.471
    JOURNAL FREE ACCESS
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    Static exercise has been thought to induce greater pressor response than dynamic exercise, but in contrast it has been recently reported that repetitive muscle contraction recruiting small muscles evokes greater response than sustained contraction. It remained unknown whether sustained contraction induces greater pressor response if large muscles were recruited. Nine subjects performed three types of isometric knee extensions recruiting the large muscle group, i.e., 2-min sustained (20% and 40% maximal voluntary contraction [MVC]) and 4-min repetitive (40% MVC, duty cycle = 1:1 s) muscle contractions. Compared under the equivalent TTI and exercising duration (2 min), the changes in femoral arterial blood flow and VO2 from baseline (ΔBF, ΔVO2) were significantly less during sustained contraction than during repetitive contraction (sustained vs. repetitive; ΔBF: +92 ± 195 vs. +1,174 ± 269 ml min−1, ΔVO2: +53 ± 12 vs. +180 ± 32 ml min−1, mean ± SE, p < 0.05), although the change in mean arterial pressure (ΔMAP) was greater during sustained contraction (+24 ± 3 vs. +19 ± 3 mmHg). Compared under the equivalent TTI and peak tension (40% MVC), ΔBF and ΔVO2 were less and ΔMAP was greater during sustained contraction (ΔBF: −296 ± 176 vs. +868 ± 272 ml min−1; ΔVO2: +104 ± 16 vs. + 212 ± 46 ml min−1; ΔMAP: +37 ± 8 vs. +20 ± 4 mmHg). Moreover ΔMAP during postexercise occlusion of the active limb was significantly greater after sustained contraction than after repetitive contraction (+17.0 ± 2.8 vs. +9.5 ± 4.4 mmHg). These results demonstrated that pressor response is greater during sustained than during repetitive contraction, recruiting a large muscle group. This finding should be mainly due to the greater accumulation of metabolites in active muscles during sustained contraction.
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  • Short-Chain Fatty Acids Decrease the Frequency of Spontaneous Contractions of Longitudinal Muscle via Enteric Nerves in Rat Distal Colon
    Shigeyuki Ono, Shin-ichiro Karaki, Atsukazu Kuwahara
    2004 Volume 54 Issue 5 Pages 483-493
    Published: 2004
    Released on J-STAGE: January 29, 2005
    DOIhttps://doi.org/10.2170/jjphysiol.54.483
    JOURNAL FREE ACCESS
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    Short-chain fatty acids (SCFAs) produced by the bacterial fermentation of carbohydrates in the cecum and proximal colon are reported to modify colonic motility as a luminal factor. Besides the physical stimuli in the distal colon, SCFAs in the intestinal lumen also seem to affect colonic motility under physiological concentrations. This study therefore used fasted rats to investigate the effect of SCFAs on the spontaneous contractions of longitudinal muscle (LM) in rat distal colon, including mucosa in vitro. The frequency of spontaneous contractions of LM strips from the distal colon was 9.4 ± 0.5 contractions/20 min. The exogenous addition of >5 mM SCFAs decreased the frequency of spontaneous contractions of the LM to 6.1 ± 0.8 contractions/20 min. Among SCFAs, only acetate elicited this inhibitory response. TTX and the combination of hexamethonium and granisetron abolished SCFA-induced inhibitory response, suggesting that this inhibitory response is mediated via the ENS, including nicotinic and 5-HT3 receptors. In conclusion, it is suggested that SCFAs in rat distal colon decrease the frequency of spontaneous contractions of the LM and that SCFAs may contribute to colonic motility, including the peristaltic reflex, by regulating the frequency of spontaneous contractions of the LM through the enteric nervous system (ENS).
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Short Communications
  • Response Patterns of Vestibulospinal Neurons to Lumbar Rotation in Decerebrate Rats
    Feng Tian, Sei-etsu Fujiwara, Takashi Yamaguchi
    2004 Volume 54 Issue 5 Pages 495-498
    Published: 2004
    Released on J-STAGE: January 29, 2005
    DOIhttps://doi.org/10.2170/jjphysiol.54.495
    JOURNAL FREE ACCESS
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    In vestibulospinal neurons projecting to the lumbar enlargement, activities were modulated in response to alternate tilts of the caudal body around the vertebral axis. Three types of neurons were found: Type I (37.8%) showed faster firing during the ipsilateral side-down tilt; type II (51.1%) showed the reverse pattern; type III were unaffected. Types I and II may be important in the tonic lumbar reflex.
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  • Ventilatory and Heart Rate Responses at the Onset of Chair Rotation in Man
    Miharu Miyamura, Koji Ishida, Keisho Katayama, Norihiro Shima, Hiroshi ...
    2004 Volume 54 Issue 5 Pages 499-503
    Published: 2004
    Released on J-STAGE: January 29, 2005
    DOIhttps://doi.org/10.2170/jjphysiol.54.499
    JOURNAL FREE ACCESS
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    In the present study, we attempted to confirm whether pulmonary ventilation and heart rate increased immediately after passive chair rotation in man. Inspiratory minute volume (VI), tidal volume (VT), respiratory frequency (f), and heart rate (HR) were determined by breath-by-breath and beat-by-beat techniques before, during, and after rotation for a total of 45 s. It was found that VI significantly increased immediately after chair rotation, but HR remained almost constant. These results suggest that the activation of horizontal semicircular canals is one causal factor of ventilatory response at the onset of exercise with rotational movement in healthy subjects, but heart rate response is not.
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Letter to the Editor
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