Juntendo Medical Journal
Online ISSN : 2188-2134
Print ISSN : 0022-6769
ISSN-L : 0022-6769
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Volume 31, Issue 2
Displaying 1-15 of 15 articles from this issue
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Contents
  • Basic Study on Decerebrate Rigidity
    -with Special Reference to the Neuronal Organization of the Tonic Neck Reflex-
    KEIJI NAKAJIMA
    1985 Volume 31 Issue 2 Pages 188-203
    Published: June 10, 1985
    Released on J-STAGE: November 20, 2014
    DOIhttps://doi.org/10.14789/pjmj.31.188
    JOURNAL FREE ACCESS
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    1 : We have studied the effects of electrical stimulation of upper cervical afferents on the forelimb extensor (triceps) and flexor (biceps) monosynaptic reflex (MSR) in chloralose-anesthetized whole brain, unanesthetized decerebrated, and spinal cats. 2 : In chloralose-anesthetized cats, stimulation of the C2 dorsal root ganglion (ggl) produced early excitation (10-30msec), followed by late inhibition (50-100msec) in both the triceps and biceps MSR. Similar effects were observed in spinal cats. 3 : On the other hand, in the decerebrated cats, the same cervical volleys induced the reciprocal effects ; excitation (10-80msec) in the triceps and inhibition (20-60msec) in the biceps MSR. 4 : Intracellular recordings from triceps and biceps motoneurons (Mn) were performed to elucidate the synaptic mechanism of the above cervical effects. In chloralose-anesthetized cats, stimulation of the ipsi- or contralateral C2 ggl evoked mainly EPSPs (latencies, 5.0-18.0msec) in triceps and biceps Mn. In spinal cats, stimulation of the ipsilateral C2 ggl evoked mainly mixed PSPs (2.5-5.5msec) in triceps Mn and EPSPs (3.0-7.5msec) in biceps Mn. The effects of contralateral C2 ggl stimulation were smaller. 5 : In unanesthetized decerebrated cats, the same cervical volleys evoked EPSPs, mixed PSPs (3.5-13msec) and IPSPs (6.5-14.5msec) in triceps and biceps Mns. It was significant that small EPSPs followed by late, long-lasting depolarization were evoked in triceps Mn. 6 : These PSPs may contribute on the above-mentioned cervical effects on the monosynaptic reflexes, and latency distribution of PSPs revealed that the synaptic linkage between the neck afferents and the forelimb Mns was apparently polysynaptic. 7 : Muscle nerves (high-threshold muscle afferent) -ventral and dorsal rami-were separately stimulated. Similar PSPs were evoked in forelimb Mns. In spinal cats, reciprocal effects were observed, i.e., stimulation of the ventral rami evoked EPSPs, whereas, that of dorsal rami evoked IPSPs in triceps Mn. 8 : Elementary synaptic circuits for Neck Reflexes seem to be located in the spinal cord. Brain stem structures (including the cerebellum), however, are indispensable for the reciprocal effects on forelimb motor activities, especially during lateral flexion in decerebration.
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  • The Feasibility and Beneficial Effects of Atrial Pacing in Sick Sinus Syndrome
    YASUYUKI TANAHASHI
    1985 Volume 31 Issue 2 Pages 204-214
    Published: June 10, 1985
    Released on J-STAGE: November 20, 2014
    DOIhttps://doi.org/10.14789/pjmj.31.204
    JOURNAL FREE ACCESS
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    The number of patients with sick sinus syndrome (SSS) who have been treated by permanent pacemaker implant has been increasing. But, the percentage of those undergoing atrial pacing is still relatively low because of the fear that these patients could later develop atrioventricular conduction disturbances. The purpose of the present study is to examine the hemodynamic effects of atrial contraction, atrioventricular conductivity and progression to chronic atrial fibrillation, and then to discuss the feasibility and beneficial effects of atrial pacing in SSS. Clinical observations and experimental studies have indicated that, when atrial contraction occurs during ventricular systole, cardiac output and ventricular systolic pressure decrease and atrial pressure increase more than when atrioventricular synchrony is maintained. There was no observed association with second or third degree atrioventricular block in 68 sick sinus patients during follow-up, in spite of some abnormalities in the electrophysiological study. Eleven patients out of 35 (31.4%) who had been paced via the ventricule showed atrial fibrillation, whereas only one out of 15 (6.7%) of those who received atrial pacemakers progressed to atrial fibrillation. These results suggest that SSS is rarely associated with atrioventricular block and that atrial pacing has beneficial effects on hemodynamics and prevention of atrial fibrillation. In conclusion, permanent atrial pacing should be chosen for pacemaker treatment of SSS.
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  • Epicardial Potential Wave Form After Epicardial Stimulation Recorded at the Same Point of Stimulation
    TAKESHI MIURA
    1985 Volume 31 Issue 2 Pages 215-225
    Published: June 10, 1985
    Released on J-STAGE: November 20, 2014
    DOIhttps://doi.org/10.14789/pjmj.31.215
    JOURNAL FREE ACCESS
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    The epicardial depolarization wave forms of both ventricles were examined to ascertain the local depolarization process at the stimulating site. Twenty-one mongrel dogs were used, and their hearts were exposed to the air through midsternal thoracotomy under artificial respiration. A single Ag/AgCl electrode was used. This electrode was nonpolarizable and its shape was spherical, 2 mm in diameter. It was attached to the heart by means of cyanoacrylate adhesives so that the electrode could contact the myocardium with constant pressure. Epicardial stimulation and epicardial potential recording could be carried out simultaneously by this electrode. In the early phase of the depolarization, the wave showed a negative plateau potential of -47.5±9.4mV (mean±SD) for the left ventricle and -40.1±8.6mV for the right ventricle. A difference in plateau potential was recognized between the two ventricles, and it was considered to be related not to wall thickness, but to electrical and morphological characteristics of the myocardial cell. The duration of this plateau potential was 32.9±4.6msec for the left ventricle and 18.3±3.7msec for the right ventricle. A simple model was introduced in which the excitation wave front was considered to be a single dipole layer and to propagate hemispherically or hemiellipsoidally. The potential induced at the center of the hemisphere was estimated from the model to be constant at about -50mV, as far as the wave front fromed a closed surface until it reached the electrical boundary of the ventricular wall. It was thought that wall thickness and conduction velocity must be responsible for the plateau duration.
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