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H Tsubone

Publications and source records attributed to H Tsubone.

At least 55 records · Page 3Linked to original sources
PubMed1997

The afferent activity of the superior laryngeal nerve, and respiratory reflexes specifically responding to intralaryngeal pressure changes in anesthetized Shiba goats.

This study was aimed at characterizing the superior laryngeal nerve (SLN) afferent activities under four different respiratory conditions, i.e., tracheostomy breathing (TB), upper airway breathing (UAB), tracheal occlusion (TO) and upper airway occlusion (UAO), and investigating respiratory changes in response to transmural pressures applied to the larynx in anesthetized Shiba goats. The activity recorded from the whole SLN increased at both inspiration and expiration during TB, UAB and TO, while an expiratory augmentation accompanied by an inspiratory inhibition was found during UAO. Based on recordings from 109 thin filament-preparations, 47 units were identified as 'drive' receptors, 31 as 'pressure' receptors (22 'positive' and 9 'negative' pressure receptors), and the rest 31 as 'non-modulated type' of receptors. The posterior cricoarytenoid (PCA) muscle activity showed a clear inspiratory modulation during UAB and was significantly enhanced by negative pressure applied to the isolated upper airway, where such an augmented activity was abolished by bilateral section of the SLN. No significant changes were found in the respiratory cycle during application of negative pressures to the larynx. The respiratory modulation of the SLN in Shiba goats was essentially identical to that reported for rabbits, rats and guinea pigs, but not in dogs. The reflex response of the upper airway muscles to the laryngeal pressure changes in Shiba goats were found to be less noticeable than in rabbits and dogs.

Airway Obstruction↗
PubMed1996

Assessment of autonomic nervous function by power spectral analysis of heart rate variability in the horse.

We studied power spectral analysis of heart rate (HR) variability in the horse, with the hypothesis that the quantitative information provided by the spectral analysis of HR variability reflects the interaction between sympathetic and parasympathetic regulatory activities. For this purpose, electrocardiogram, blood pressure (BP) and respiratory (Resp) waveform were simultaneously recorded from Thoroughbred horses (3-5 years old) and analyzed by power spectrum. There were two major spectral components at low-frequency (LF) and high-frequency (HF) bands for HR variability. The peak of Resp variability clearly occurred at the HF range. In contrast to Resp variability, the power spectra of BP variability occurred at lower frequencies. The maximum coherence between HR and Resp variabilities and HR and BP variabilities occurred at approximately 0.15 and approximately 0.03 Hz, respectively. These relationships were similar to the ensemble spectra. On the basis of these data, we have defined two frequency bands of interest: LF (0.01-0.07 Hz) and HF (0.07-0.6 Hz). Therefore, we believe that power spectral analysis of HR variability provides a very powerful technique for assessing autonomic nervous activity in the horse.

Animals↗
PubMed1996

Cardiovascular responses mediated by two types of endothelin ET(B) receptor in spontaneously hypertensive and Wistar-Kyoto rats.

This study shows the effects of a selective endothelin ET(B) receptor agonist, IRL 1720 {Ac-[Ala11,15]endothelin-1-(8-21)}, on cardiovascular responses in anesthetized spontaneously hypertensive rats and Wistar-Kyoto rats. Single intravenous bolus injection of IRL 1720 caused a dose-related short-lasting fall in blood pressure, left ventricular pressure and myocardial contractility. However, repeated intravenous bolus injection of 10(-5) mol/kg IRL 1720 produced a biphasic response consisting of an initial short-lasting decrease followed by a sustained increase in these parameters. The initial decrease was reduced, whereas the following increase was enhanced with the repeated injections of IRL 1720. The cardiovascular pressor response was not inhibited by the endothelin ET(A) receptor antagonist, FR139317 ((R)2-[(R)-2-[(S)-2-[[1-(hexahydro-1H-azepinyl)]carbonyl] amino-4-+methylpentanoyl] amino-3-[3-(1-methyl-1H-indolyl)]propionyl]amino -3- (2-pyridyl)propionic acid). The effects of IRL 1720 were qualitatively similar but more potent in spontaneously hypertensive rats than in Wistar-Kyoto rats. These results suggest the existence of two types of endothelin ET(B) receptor for IRL 1720: a tachyphylactic endothelin ET(B) receptor that mediates cardiovascular depressor responses and a less tachyphylactic endothelin ET(B) receptor that mediates pressor responses in the rat.

Animals↗
PubMed1996

Nasal receptors responding to cold and l-menthol airflow in the guinea pig.

The aim of this study was to demonstrate the presence of nasal 'cold' receptors, through recordings of action potentials from the ethmoidal nerve (EN), in guinea pigs and to characterize their responsiveness to l-menthol and capsaicin. Constant flows (400 ml/min) of room air (20 degrees C), warm air (45 degrees C), room air containing l-menthol, and cold air (-5 degrees C) were directed into the nasal cavity in the inspiratory direction via a nasopharyngeal catheter in the anesthetized guinea pigs breathing spontaneously through a tracheostomy. The ethmoidal afferent activity was increased by cold air, and to a greater extent by l-menthol but hardly by warm air. After topical anesthesia of the nasal cavity with 2% lidocaine, cold air and l-menthol no longer stimulated the EN. L-menthol noticeably stimulated the EN even after repeated capsaicin instillation into the nose, but these values were lower than those following the l-menthol stimulus before the 1st capsaicin treatment. These results suggest that the ethmoidal nerve in guinea pigs has cold-sensitive receptors which consist of both small myelinated fibers and C-fiber endings.

Action Potentials↗
PubMed1996

Nasal mechanoreceptors in guinea pigs.

The characteristics of nasal mechanoreceptors in the ethmoidal nerve (EN) of guinea pigs were clarified by electrophysiological identification of their responsiveness to transmural pressure, i.e., the inspiratory effort induced by tracheal occlusion and probing of the nasal cavity, vestibule or alae nasi of the nose. A total of 73 mechanoreceptors were recorded from 18 guinea pigs breathing through the nose or a tracheostomy with an isolated nasal airway. Six receptors (6/22) in nasal-breathing animals were stimulated by upper airway occlusion, and 18 receptors (18/22) in tracheostomy-breathing animals were stimulated by maintained negative pressure in the nose. Mechanoreceptors responding to probing to the nose were found in both experimental set-ups. The mean threshold of 'pressure'-responsive receptors to negative pressure was very high (-3.87 +/- 0.95 kPa). Most of the receptors were also examined for response to ammonia vapour or instillation of distilled water; only three 'touch'-responsive receptors could be stimulated by ammonia and/or distilled water. These results suggest low sensitivity to pressure changes and noxious chemical stimuli of mechanoreceptors in the EN of guinea pigs.

Animals↗
PubMed1996

Autonomic nervous function in mice and voles (Microtus arvalis): investigation by power spectral analysis of heart rate variability.

We have studied the autonomic nervous function in voles (Microtus arvalis) and mice. For this purpose, ECGs were recorded from conscious and unrestrained voles and mice using radiotelemetry and the autonomic nervous function was investigated by the power spectral analysis of heart rate variability. Heart rate in voles was lower than mice and the coefficient of variance was larger in voles. In the power spectra of voles and mice, there were two major spectral components with the high frequency (HF) peak generally appearing between 2.0 and 4.0 Hz, and the low frequency (LF) peak appearing below 0.6 Hz. On the basis of this data, we set the two frequency bands as LF (0.1-1.0 Hz) and HF (1.0-5.0 Hz) to evaluate autonomic nervous function. The LF and HF powers were larger in voles than mice. The LF/HF ratio was thought to provide a convenient index of autonomic nervous balance and was smaller in voles than mice. The LF powers in both species were reduced by atropine, but propranolol reduced the LF power only in mice. The HF power was reduced by atropine only in voles. The intrinsic heart rate produced by a double blockade with atropine and propranolol in voles was almost the same as control levels, but in mice was lower than controls. The ratio of the LF and HF powers by a double blockade were almost the same as those of the administration of atropine in voles, but nearer to propranolol in mice. These results suggested that the parasympathetic nervous function was predominant in voles, but the sympathetic one was predominant in mice.

Animals↗
PubMed1996

The telemetric monitoring of heart rate, locomotor activity, and body temperature in mice and voles (Microtus arvalis) during ambient temperature changes.

We have studied the physiological and behavioural responses in small rodents to ambient alterations. For this purpose, voles and mice were exposed to relatively low (12 degrees C) and high (35 degrees C) ambient temperatures, and heart rate (HR), locomotor activity (LA) and body temperature (BT) were recorded using telemetry system. The control HR (at 24 degrees C) of voles was lower than that of mice. The 'heat exposure' decreased HR to 85.0 +/- 3.3% in voles, and to 78.0 +/- 3.2% in mice compared with the mean HR of the same time in the control day. The 'cold exposure' increased the HR to 131.9 +/- 8.8% in voles, and 119 +/- 10.9% in mice. The decreasing rate of HR in heat exposure was smaller in voles than mice, and in cold exposure the increased rate was larger in voles than mice. Cold exposure decreased BT in both species; 96.1 +/- 0.5% in voles and 93.7 +/- 1.0% in mice. The LA was not changed significantly by heat exposure in either species, but was partially increased by cold exposure. These results demonstrate that telemetry was helpful for qualitative and quantitative behavioural studies in small rodents, and confirmed that the physiological and behavioural responses to ambient temperature changes differed between these animals.

Animals↗
PubMed1996

Cardiopulmonary responses to capsaicin instillation to the laryngeal lumen and their reflex mechanisms in rats.

Cardiorespiratory effects of capsaicin (CAPS) solution instilled into the larynx and the reflex mechanisms were investigated in rats with spontaneous breathing or under artificial ventilation. The first challenge with CAPS (100 micrograms/ml, 20 microliters) markedly inhibited spontaneous breathing due to a considerable prolongation of expiration time (TE) (1785% of control) in all rats. Circulatory changes such as hypertension (mean systolic blood pressure-210 mmHg) and bradycardia (10.5% decrease in heart rate) were also elicited by the 1st challenge with CAPS. These changes were largely reduced by the second challenge of CAPS; but not abolished in 3 of 5 rats by bilateral section of the superior laryngeal nerves (SLNs) and recurrent laryngeal nerves (RLNs). The bradycardia and hypertension after the CAPS-instillation were able to be elicited to the same extent in rats in the absence of apnea under artificial ventilation. The bradycardia was entirely abolished by pretreatment with atropine injection, while the hypertension was largely inhibited by phentolamine and propranolol. These results demonstrated that the laryngeal and/or pharyngeal noxious stimulus could induce marked cardiorespiratory reflexes, where the circulatory changes could be elicited in the absence of apnea, suggesting the presence of eliciting mechanisms of circulatory changes independent on the occurrence of apnea. In addition, it was also suggested that those cardiorespiratory responses were mediated by the afferents such as unmyelinated C-fiber endings and thin myelinated fibers and by the efferents, both the parasympathetic and sympathetic nervous systems.

Animals↗
PubMed1996

Threshold changes in auditory brainstem response (ABR) due to the administration of kanamycin in dogs.

Auditory brainstem response (ABR) is a useful method in evaluating auditory function in human. To investigate the ABR threshold is more effective than to pursue the trends in each component of ABR. In this study, tone burst sound stimuli were employed and the ABR threshold shift caused by kanamycin administration was investigated in dogs. In a series of monitoring of ABR against short-period auditory lesions, changes in the ABR waveform after intravenous administration of kanamycin were detected. These changes returned gradually and were reversible. The changes in ABR against long-period auditory function disorder were perceived by an increase in the ABR threshold. The ABR threshold shift occurred earlier in the high frequency sounds than in the lower frequency sounds. This is why amino glycoside antibiotics damage the cochlear hair cells in the basal layer and lead to the loss of hearing selectively for high frequency tones. These findings suggest that tracing of the ABR threshold by tone bursts could provide information that has a specificity for frequency in hearing tests and is a useful method in clinical veterinary medicine or/and toxicological tests.

Animals↗
PubMed1996

Non-invasive measurement of systemic arterial pressure in guinea pigs by an automatic oscillometric device.

BACKGROUND: There is no useful oscillometric device to measure the systemic arterial pressure in small experimental animals except rats. Therefore we evaluated a recently developed automatic oscillometric device for the indirect blood pressure measurement in guinea pigs.METHODS: Twenty male Hartley guinea pigs were used. We found that unanaesthetized guinea pigs stayed comfortably in a guinea pig-holder without training. A pneumatic cuff was placed snugly around the crus of the left limb. Cuff size was selected according to previous recommendations (cuff width = limb circumference x 0.4). Systolic blood pressure corresponded to the point at which oscillations began to increase; mean arterial pressure corresponded to the point at which the oscillations peaked. Diastolic blood pressure was calculated from the values of systolic and mean blood pressures. To test the accuracy of this device, the direct and indirect values were arbitrarily collected from simultaneous recordings of six anaesthetized guinea pigs with various levels of blood pressure induced by intravenous noradrenaline infusions. RESULTS: The oscillometric device for indirect blood pressure measurements allows the measurement of blood pressure easily and quickly. Twenty unanaesthetized guinea pigs had a heart rate of 280.0 +/- 6.7 beats/min (mean +/- SEM) and systolic, mean and diastolic blood pressures of 94.0 +/- 2.2, 63.6 +/- 1.7 and 48.4 +/- 1.6 mmHg, respectively. These values are almost the same as those found in earlier studies. Correlation coefficients between direct and indirect values were > 0.9 for all blood pressures. CONCLUSIONS: These results suggest that this device may be valuable for monitoring systemic arterial blood pressure in guinea pigs.

Journal Article↗
PubMed1995

Sensory information from the upper airway: role in the control of breathing.

The functional integrity of extrathoracic airways critically depends on the proper orchestration of the activities of a set of patency-maintaining muscles. Recruitment and control of these muscles is regulated by a laryngeal and trigeminal affects that originate from pressure sensing endings. These sensors are particularly numerous among laryngeal receptors and, indeed, they constitute the main element in the respiration-modulated activity of the superior laryngeal nerve. Considering that the most compliant region of the upper airway, and thus more vulnerable to inspiratory collapse, lies cranially to the larynx, the laryngeal pressure-sensing endings seem to be ideally located for detecting collapsing forces and initiating reflex mechanisms for the preservation of patency. This process operates by activating upper airway dilating muscles and by decreasing inspiratory drive: both actions limit t he effect of the collapsing forces. Cold reception is differently represented in various mammalian species within nasal and laryngeal segments. Cooling of the upper airway has an inhibitory influence on breathing, especially in newborns, and a depressive effect on upper airway dilating muscles. The latter response is presumably mediated through the inhibitory effect of cooling on laryngeal pressure endings. These responses could be harmful during occlusive episodes. Powerful defensive responses with distinct characteristics can be elicited through the simulation of laryngeal and nasal irritant type receptors. Sneezing is elicited through the stimulation of trigeminal afferents, cough through the stimulation of laryngeal vagal endings. Changes in osmolality and ionic composition of the mucosal surface liquid can lead to conspicuous alterations in receptor activity and related reflexes.

Afferent Pathways↗
PubMed1995

DMI-1, a new DNA methyltransferase inhibitor produced by Streptomyces sp. strain No. 560.

A new inhibitor of DNA methyltransferase named DMI-1 has been discovered in the culture filtrate of Streptomyces sp. strain No. 560. DMI-1 was purified by extraction with ethyl acetate followed by Diaion HP-20SS and silica gel column chromatography. The structure of DMI-1 was determined to be 8-methylpentadecanoic acid (C16H32O2). DMI-1 is a novel inhibitor of methyltransferase isolated from microorganisms and is structurally different from sinefungin and A9145C which are structural analogs of S-adenosylmethionine (methyl donor). DMI-1 was a strong inhibitor of N6-methyladenine-DNA methyltransferase (M. Eco RI, EC 2.1.1.72) in a noncompetitive manner and its inhibition depended on the pH and temperature in the assay media.

DNA Modification Methylases↗
PubMed1994

Nasal receptors responding to noxious chemical irritants.

This study was performed to investigate the chemoreception of trigeminal afferents in the nose. Single unit activity was recorded from the anterior ethmoidal nerve in the anesthetized guinea pig breathing through a tracheostomy during nasal instillation of capsaicin (0.3 mM), nicotine (6 mM) and ammonia (1.5 M) solutions or with distilled water. Out of 36 fibers recorded, nineteen were stimulated by capsaicin, six by nicotine and seventeen by ammonia. Among those fibers, two were stimulated by both capsaicin and nicotine, six by both capsaicin and ammonia and one nicotine-responsive fiber was also stimulated by ammonia. A large proportion of capsaicin- and nicotine-responsive fibers exhibited long lasting discharges (170.4 +/- 17.7 sec and 120.7 +/- 29.3 sec, respectively), and were not stimulated by the second application of the same substance. However, fibers responding to ammonia discharged for a shorter time (31.5 +/- 6.5 sec), indicating a rapid adaptation. These results indicate that the ethmoidal nerve possesses a well-developed responsiveness to noxious stimuli. The nociceptive component of this nerve may be related to the various cardiorespiratory responses that can be elicited from the nasal cavity and also to local axonal reflexes (neurogenic inflammation) due to the release of chemical mediators from C-fiber endings.

Ammonia↗
PubMed1994

Power spectral analysis of heart rate variability as a new method for assessing autonomic activity in the rat.

The authors studied power spectral analysis of heart rate variability in the rat, hypothesizing that the quantitative information provided by this analysis reflects the interaction between sympathetic and parasympathetic regulatory activities. For this purpose, an electrocardiogram was recorded from conscious and unrestrained Wistar rats (Nippon, Shizuoka) (12-16 weeks old) by a telemetry system and analyzed by a power spectrum. Because it was thought that the electrocardiogram recorded by the telemetry system could provide more reliable data to assess autonomic nervous activity than the tethering system, the telemetry recording system was used. There were two major spectral components in the power spectrum at low frequency (LF) (0.6 Hz) and high frequency (HF) (approximately 1.4 Hz). On the basis of these data, the authors defined two frequency bands of interest: LF (0.04-1.0 Hz) and HF (1.0-3.0 Hz). The power of LF was higher than that of HF in the normal rat. Atropine (2 mg/kg intraperitoneally) significantly reduced both HF and LF power. Propranolol (4 mg/kg intraperitoneally) also significantly reduced LF power; however, it had no significant effect on HF power. Thus, this study in the rat confirmed earlier observations in the conscious dog and human. Furthermore, the decrease in the parasympathetic mechanism produced by atropine was reflected by a slight increase in the LF/HF ratio. The LF/HF ratio appeared to follow the reductions of sympathetic activity produced by propranolol. From these results, the LF/HF ratio seemed to be a convenient index of parasympathetic and sympathetic interactions in the rat.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Studies on the autonomic nervous function in Tsukuba emotional rats--with special reference to their cardiac function.

Autonomic nervous function in Tsukuba high (THE) and low (TLE) emotional rats as well as Wistar rats (control) was studied by means of electrocardiographical examination in addition to the runway test. In the runway test, locomotive activity differed significantly among the three strains, the greatest activity in TLE and the smallest in THE. Electrocardiogram (ECG) and locomotive activity were successively recorded for 24 hr using a small size of telemeter system. Though the locomotive activity showed a clear nocturnal rhythm, no significant difference was observed among the three strains. The mean value of R-R intervals in THE tended to be smaller than those in other two strains; showing a significant difference between THE and TLE. The mean value of standard deviation (SD) of R-R intervals in TLE tended to be larger than those in other two strains; showing a significant difference between TLE and Wistar in the light and dark periods, and also between TLE and THE in the light period. As regards coefficients of variation of R-R intervals (CV), there was no significant difference among the three strains. Autonomic nervous tone in THE and TLE was evaluated by means of autonomic blockades using atropine and/or propranolol. The sympathetic nervous tone represented 21.6% in THE and 16.8% in TLE, while the parasympathetic nervous tone -9.0% and -12.3% in THE and TLE, respectively. There was a significant difference in the net autonomic nervous tone between THE (10.7%) and TLE (-6.6%).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

The disturbance of water-maze task performance in mice with EMC-D virus infection.

The present study was performed to examine the influence of EMC-D virus on water-maze task performance in DBA/2 mice inoculated with 10(3) PFU/ml and BALB/c mice inoculated with 10(5) PFU/ml of EMC-D virus. In both strains, the latency to accomplish the task was shortened during successive 8 days of testing. However, the shortening of latency in the inoculated group was significantly smaller than that in the control group. Pathological studies showed that in both studies St. pyramidale hippocampi was commonly degenerated, but the degeneration of the spinal cord was shown only in DBA/2 mice. Therefore, the disturbance of water-maze task performance in mice infected with EMC-D virus might be partially due to the dysfunction of memory for working process or cognition of orientation other than underlying decreased ability in locomotion.

Animals↗
PubMed1993

[Diurnal fluctuations of heart rate and locomotive activity in the vole (Microtus arvalis)].

Diurnal fluctuations of heart rate and locomotive activity were observed in the unanesthetized and unrestrained voles (Microtus arvalis) and mice, and the differences in these biological characters between voles and mice were also investigated. The mean heart rate of vole in whole day was lower than that of mice. In voles, there were no significant differences in the mean heart rate between in light period and in dark period. It was observed that most of voles were active in not only dark period but light period. On the other hand, in mice, the mean heart rate in dark period was significantly higher than that in light period, and the nocturnal habit was shown obviously in the locomotive activity. In voles, the ultradian rhythmicities of 95-210 min in the heart rate and those of 160-210 min in the locomotive activity were recognized, and the fluctuations of heart rate due to ultradian rhythmicity in voles exceeded the difference between the heart rate in light period and that in dark period. In mice, one of three animals showed the ultradian rhythmicity of 85 min in the fluctuation of heart rate. Diurnal fluctuation of the heart rate in voles consisted of the two patterns which the peaks of heart rate were coincident with the active period or the resting period. However, all the peaks of heart rate in mice were coincident with the active period. These results suggested that the fluctuations of heart rate in voles were dependent on ultradian rhythmicities in addition to the circadian rhythmicities.

Animals↗