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Volume 53, Issue 1
Displaying 1-9 of 9 articles from this issue
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Regular Papers
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Eitaro Noguchi, Hideo Ohsawa, Hideki Tanaka, Hiroko Ikeda, Yoshihiro A ...2003 Volume 53 Issue 1 Pages 1-7
Published: 2003
Released on J-STAGE: June 19, 2004
JOURNAL FREE ACCESSThe effect of electro-acupuncture stimulation (EAS) on duodenal motility was examined in anesthetized, artificially ventilated rats. EAS was applied to the abdominal area or to a hindpaw for 30 s at stimulus intensities of 0.1–10.0 mA with a stimulus frequency of 20 Hz. The duodenal motility was measured using the balloon method at a position about 1.5 cm caudal from the pylorus. Duodenal motility was inhibited by EAS at intensities of more than 5.0 mA (suprathreshold of group IV afferent excitation) when applied to the abdominal area. The duodenal inhibitory response existed after bilateral vagotomy or spinal transection, but was abolished by sectioning bilateral splanchnic nerves. Duodenal motility was facilitated by EAS at intensities of more than 2.0 mA (subthreshold of group IV, and supurathreshold for groups II+III afferent excitation) when applied to a hindpaw. The duodenal facilitatory response by EAS to a hindpaw existed after sectioning the splanchnic nerves, but disappeared after bilateral vagotomy or spinal transection. Furthermore, repetitive electrical stimulation of vagal efferent nerves enhanced duodenal motility, while repetitive electrical stimulation of the splanchnic efferent nerves inhibited the motility. It was concluded that the inhibitory response of duodenal motility elicited by EAS to the abdominal area is a spinal reflex response involving splanchnic inhibitory efferent nerves, and the enhanced response of duodenal motility by EAS to a hindpaw is a supraspinal reflex response involving vagal excitatory nerves.
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Tomoyuki Maeda, Koichi Mori, Yoshimitsu Shiraishi, Kyoko Tatebayashi, ...2003 Volume 53 Issue 1 Pages 9-15
Published: 2003
Released on J-STAGE: June 19, 2004
JOURNAL FREE ACCESSParaplegia is a devastating complication of operations requiring transient occlusion of the descending thoracic aorta. Many animal models of spinal cord ischemia have been utilized to examine the efficacy of various neuroprotective methods. In this study, we establish a rabbit model of spinal cord ischemia by selective temporary occlusion of lumbar arteries and examine the protective effects of systemic mild hypothermia in this model. Animals were divided into the following four groups: sham group (group A, n = 6); 10 min ischemia, normothermia (39°C) (group B, n = 6); 20 min ischemia, normothermia (group C, n = 6); and 30 min ischemia, mild hypothermia (35°C) (group D, n = 6). After 7 d of reperfusion, three rabbits in group B and five rabbits in group C developed paraplegia (Tarlov's score = 0). In contrast, all rabbits preserved hindlimb motor function (Tarlov's score = 4) in groups A and D. Histological findings indicated that the number of motor neurons in the anterior horns in group C were significantly fewer than in group A. A large number of motor neurons were preserved in group D. Hypothermia is known to be an effective and reliable method of neuroprotection, but the risk of complications rises at deep hypothermia. Our current results confirm that systemic, mild hypothermia is a safe and effective neuroprotective method during ischemia-reperfusion injury of the spinal cord.
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Miharu Miyamura, Koji Ishida, Keisho Katayama, Yasutake Sato, Yoshifum ...2003 Volume 53 Issue 1 Pages 17-24
Published: 2003
Released on J-STAGE: June 19, 2004
JOURNAL FREE ACCESSIn order to clarify whether or not ventilatory and circulatory responses to hypoxia and hypercapnia at rest in male vocalists (n = 11) are identical to those of untrained subjects (n = 11), ventilatory responses to hypoxia (HVR) and hypercapnia (HCVR) were estimated as the slope of regression relating V˙I to SaO2 (ΔV˙I/ΔSaO2) or the slope factor (A) for the V˙I–PETO2 curve, and as the slope of regression relating V˙I to PETCO2 (ΔV˙I/ΔPETCO2), respectively. The respiratory frequency (f), tidal volume (VT), heart rate (HR), and blood pressure (BP) responses to hypoxia and hypercapnia were also estimated as the slope of the line calculated by linear regression related to SaO2 and PETCO2. Mean values of ΔV˙I/ΔSaO2 and A as an index of hypoxic ventilatory response were lower in the vocalist group (0.39 ± 0.25 l·min−1·%−1 and 76.8 ± 55.7 l·min−1·torr−1) than that in the control group (0.56 ± 0.46 l·min−1·%−1 and 101.6 ± 85.4 l·min−1·torr−1), and there was no statistically significant difference. The Δf/ΔSaO2 was significantly (plt;0.05 ) lower in the vocalist group (−0.02 ± 0.39 breaths·min−1·%−1) than that in the control group (0.43 ± 0.65 breaths·min−1·%−1). In contrast, mean values of ΔV˙I/ΔPETCO2 per body mass index were significantly (plt;0.05) lower in the vocalist group (0.05 ± 0.03 l·min−1·torr−1) than those in the control group (0.10 ± 0.06l·min−1·torr−1). There were also significant differences in ΔVT/ΔPETCO2 and Δf/ΔPETCO2 between the two groups (plt;0.05). However, no significant differences in HR and BP responses to hypoxia and hypercapnia between the two groups were observed. These results suggest that the magnitude of ventilatory response, but not HR and BP, to hypoxia and hypercapnia at rest in vocalists is reduced by chronic vocal training, including breath control and elongation of phonation for long periods.
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Hirofumi Shimizu, Chikashi Toyoshima, Shigetoshi Oiki2003 Volume 53 Issue 1 Pages 25-34
Published: 2003
Released on J-STAGE: June 19, 2004
JOURNAL FREE ACCESSThe fast inactivation of the human ether-à-go-go related gene product (HERG) channel is a form of C-type inactivation and is decelerated by external tetraethylammonium (TEA) and potassium. From the time constant of inactivation, the dissociation constants of TEA (KTEA) and potassium (KK) to the inactivation-impeding site were evaluated. KTEA was found to exhibit unexpected voltage dependence: KTEA decreased with depolarization. This was opposite the voltage dependence of KK on inactivation, in which permeating potassium impeded closure of the inactivation gate upon binding to a site in the pore (a "foot-in-the-door" mechanism). Further experiments on inactivation revealed anomalous mole fraction effects between permeating alkali cations and TEA, while no anomalous effects were seen between permeating ion species (K+, Rb+, Cs+). The results indicate that TEA and permeating ions impede inactivation through binding to different but closely interacting sites. KTEA was influenced by permeating ions through their bindings in the pore. As the size of the occupied ion was increased the dissociation constant of TEA to the ion-occupied pore decreased. Thus, we conclude that an ion bound to the inactivation-impeding site in the selectivity filter is located in close proximity to TEA bound at the entrance of the filter. The order of affinity of alkali cations for the inactivation-impeding site, Rb+ > Cs+ > K+, indicated that the selectivity of the site differed significantly from permeation selectivity, K+ > Rb+ > Cs+.
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Atsuko Takamaki, Yoshiaki Mori, Michitoshi Araki, Akihito Mineharu, Yo ...2003 Volume 53 Issue 1 Pages 35-44
Published: 2003
Released on J-STAGE: June 19, 2004
JOURNAL FREE ACCESSUsing Ca2+-selective microelectrodes based on the neutral carrier, ETH-1001 with polyvinyl chloride (PVC), we have measured changes in the free Ca2+ concentration of guinea pig cochlear endolymph ([Ca]e) after transient asphyxia or intravenous administration of diuretics. Under the control conditions, the endocochlear potential (EP) was +80 mV, and the [Ca]e was in the range 1.4×10−7–2.4×10−6 M (n = 16). Transient asphyxia (1–1.5 min) produced an increase in the [Ca]e with a fall in the EP, whereas the cessation of the asphyxia led to a quick recovery of both [Ca]e and EP to their control levels. Intravenous administration of furosemide (60 mg/kg) or bumetanide (30 mg/kg) also caused an increase in the [Ca]e with a fall in the EP, followed by a gradual recovery of both [Ca]e and EP. From these results, we obtained a significant correlation between EP and p[Ca]e (= –log[Ca]e), and conclude that (1) the [Ca]e is extremely low, around 10−6 M or less, under normal conditions and (2) the [Ca]e is directly correlated with EP under physiological conditions.
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Masanori Nagai, Maki Wada, Yumie Kobayashi, Shinobu Togawa2003 Volume 53 Issue 1 Pages 45-51
Published: 2003
Released on J-STAGE: June 19, 2004
JOURNAL FREE ACCESSWe examined the possibility that lumbar skin warming can increase gastrointestinal motility by investigating the electrogastrogram (EGG), blood pressure, and heart rate with psychometric ratings in healthy humans. Scores of mood state profiles showed that lumbar skin warming (42°C, 20 min) decreased tension-anxiety, depression, anger-hostility, fatigue, and confusion of the participants. A multiple bandpass filter analysis of EGGs showed that a postural transition from orthostatic to supine for measurement caused an increase in dominant frequency of 25–29% towards the frequencies of the normal interdigestive migrating motor complex (IMC). The spectral power of the IMC band, 2.55–3.05 cycles/min, was increased by 20 min-warming, reflecting the increase in gastric contractility. No increase in the spectral power was observed in the time-matched control group without skin warming. Therefore, an increase in contractility is a characteristic of lumbar skin warming. The systolic blood pressure increased by 15% during warm stimulation. Interbeat intervals were not influenced by warm stimulation. An analysis of interbeat intervals by a fast Fourier transform method showed that the cardiac sympathetic and parasympathetic nerves did not play a major role in raising the blood pressure. Vasoconstriction of the mesenteric artery was therefore considered to cause a blood pressure increase during warming. It is hypothesized that vasoconstriction of the visceral arteries by lumbar skin warming increases the blood pressure and gastrointestinal contractility.
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Akihiko Yamaguchi, Yasuhiro Ikeda, Toshihiro Hirai, Takahiko Fujikawa, ...2003 Volume 53 Issue 1 Pages 53-60
Published: 2003
Released on J-STAGE: June 19, 2004
JOURNAL FREE ACCESSWe investigated whether local insulin-like growth factor-I (IGF-I) mRNA and growth hormone (GH) receptor mRNA expressions in plantaris muscle were related to the region-specific hypertrophy following compensatory overload. Adult male normal or hypophysectomized rats were subjected to unilateral distal-half removals of the gastrocnemius and soleus muscles. The contralateral hindlimb was used as the control. Two weeks later, fiber areas in the distal and proximal parts of the plantaris muscle were measured. All the fiber areas measured in the distal part of the plantaris muscle in normal and hypophysectomized rats were significantly increased following the compensatory overload. In the proximal part, fiber areas of type I, IIA, and IIC were significantly increased, but fiber area of type IIB did not change. IGF-I mRNA expressions in the distal and proximal parts were increased 3 d after the compensatory overload in normal and hypophysectomized rats. The increase of IGF-I mRNA expression in the distal part 3 d after compensatory overload was greater than those in the proximal part. IGF-I mRNA expressions in the distal and proximal parts were increased 14 d after the compensatory overload in hypophysectomized rats, but not in normal rats. GH receptor mRNA expressions were decreased following compensatory overload, and almost disappeared 14 d after the compensatory overload in hypophysectomized rats. Thus muscle fiber hypertrophy following compensatory overload was different among the parts in a muscle and IGF-I mRNA was expressed in concert with the region-specific hypertrophy, but not GH receptor mRNA.
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Technical Notes
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Kanji Matsukawa, Hidehiko Komine, Hirotsugu Tsuchimochi, Jun Murata, Y ...2003 Volume 53 Issue 1 Pages 61-64
Published: 2003
Released on J-STAGE: June 19, 2004
JOURNAL FREE ACCESSWe have developed two new types of bipolar cuff microelectrodes (volume size, 2–3 mm3) using electro-conductive rubber or water-absorbent polymer, either of which can be applied to measure sympathetic nerve activity in small animals. A renal nerve bundle of an anesthetized rat was inserted into the center hole of the electrode (diameter, 0.15 mm) through a slit and had good contact with the electrodes. Renal sympathetic nerve activity, which was verified by sympathetic ganglionic blockade, could be recorded using either type of implantable cuff electrode.
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Mihoko Tomida, Masashi Kimura, Kazuo Kuwata, Tomoya Hayashi, Yukio Oka ...2003 Volume 53 Issue 1 Pages 65-69
Published: 2003
Released on J-STAGE: June 19, 2004
JOURNAL FREE ACCESSWe have developed an expression system for recombinant human serum albumin (rHSA) using methylotrophic yeast Pichia pastoris Mut+ transformants together with the multiple cross-over integration of the vector containing human serum albumin (HSA). After 86 h of methanol induction, the secreted rHSA reached levels of ∼320 mg/l in 100% H2O medium and ∼180 mg/l in 70% D2O/30% H2O (v/v) medium in a fed-batch fermenter. The structures of the obtained rHSA and plasma-derived HSA (pHSA) were virtually identical as viewed from various physicochemical techniques such as HPLC, SDS gel electrophoresis, and CD. NMR peaks of the partially deuterium (D)-labeled rHSA (DrHSA) were quite sharp compared to those of pHSA due to suppression of the intramolecular nuclear Overhauser effect, promising further structural studies of the whole HSA molecule in the solution state using the recent NMR techniques.
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