Michio Chiba

Further Observations of the Digital Plethysmography in Response to Auditory Stimuli and Its Clinical Applications

Further observations of the digital plethysmography with auditory stimuli and its clinical applications were performed in patients with vibration disease and heart diseases. The responsive pattern to the auditory stimuli in the digital plethysmogram could be faithfully reproducible if it elapses more than 5 minutes apart between the first stimulus and the second one. The responsive patterns were divided into four types: normal (N), hyperreactive (I and D) types and hyporeactive (P) type.1 The values of urinary catechol amine increased in parallel to the activity level of the autonomic nerve. The hyperreactive type (D) had the highest value of urinary catecholamine, and vice versa. With regard to the age, the elderly was prone to show hyporeactive (P) type, and the young tended to be hyperreactive (D) type. Psychologic factors were examined by Cornell medical index. Neurosis was not necessarily related to the hyperreactive type. In clinical applications, it was observed by this method that the autonomic imbalance in patients with vibration disease, angina pectoris, or hypertension was recovered by the treatment, and the abnormal types of the response recovered to N type. In conclusion, the digital plethysmography with auditory stimuli as one of the autonomic nerve function tests would be much useful and non-invasive method for observation of clinical course and decision of the severity.

Role of adrenergic receptor systems in canine left ventricular hypertrophy

Although the sympathetic nervous system and catecholamines have been postulated to play an important role in the development of myocardial hypertrophy, the precise mechanism is still ill-defined. We therefore investigated myocardial norepinephrine and the adrenergic receptor systems in two experimental canine models for cardiac hypertrophy; in 12 dogs with surgical cardiac denervation, and in 12 dogs with chronic infusion of a subhypertensive dose of norepinephrine at a rate of 0.04 mg/kg/day. After two months both models induced myocardial hypertrophy, indicated by significant increases in the heart weight, left ventricular wall thickness and cell diameter, as compared with 14 sham-operated control dogs. Cardiac denervation remarkably depleted myocardial norepinephrine while plasma norepinephrine remained unchanged. Both alpha 1- and beta-receptors were up-regulated, with Bmax increasing by 124% and 49%, respectively. The decrease in myocardial cyclic AMP content was relatively small as compared with the marked depletion in myocardial norepinephrine, probably compensated by augmentation of beta-receptor system activity. Chronic norepinephrine infusion also reduced myocardial norepinephrine content possibly due to stimulation of presynaptic alpha 2-receptor inhibiting norepinephrine synthesis and release. The number of alpha 1- and beta-receptors also increased by 97% and 30%, respectively, while myocardial cyclic AMP content remained unchanged. These observations indicate that neither direct stimulation of norepinephrine on the myocardial cell nor increased cyclic AMP is the mechanism for cardiac hypertrophy. A greater increase in the alpha 1-receptor, rather than in the beta-receptors, in both models implies that a disproportional augmentation of the alpha 1-receptor system may play an important role in the development of myocardial hypertrophy.

Cardiac hypertrophy in surgically denervated dogs with aortic stenosis

Left ventricular cell hypertrophy in dogs with aortic stenosis was accelerated by surgical denervation of the left ventricle. We conclude that there are neural mechanisms which, when present, inhibit cardiac cell hypertrophy.

Responses of Myocardial Blood Flows to Whole-Body Vibration in the Dog

Experimentally acute exposure to whole-body vibration resulted in changes in myocardial blood flows in the in vivo dog. Regional myocardial blood flows measured by a hydrogen gas clearance method were increased at a vibration frequency of 120 Hz and decreased at 50 Hz. No appreciable changes were found in presence of a beta-adrenergic blocker. The values of plasma cyclic nucleotides were increased at both frequencies of vibration, more at 50 Hz than at 120 Hz. No significant changes were observed in heart rates and arterial pressure during and after vibration load. These findings suggest that increased myocardial blood flows in response to vibration may be related more to the frequency of vibration than to beta-adrenergic actions.

Noninvasive assessment of the autonomic nervous tone in angina pectoris: an application of digital plethysmography with auditory stimuli.

To assess the relationship between autonomic nerve activity and the angi nal attack, we examined the daily variation of the autonomic tones employing digital plethysmography with auditory stimuli, and also tested the daily varia tion of exercise capacity. Thirteen of 45 cases (28.9%) of spontaneous angina, excluding Prinzmetals angina, complained of typical chest discomfort or pain especially in the morning. They manifested an augmented level of the au tonomic nerve activity and positive stress testing. The remainder did not demonstrate these abnormal findings in the morning. For the 13 cases, calcium antagonists were given orally immediately after awakening. This resulted in the complete relief from chest discomfort or pain. These findings suggest that an autonomic imbalance plays an important role in the pathogenesis of this type of anginal attack. Thus, the estimation of the daily variation of autonomic nerv ous tone would be valuable for the diagnosis and treatment of angina pectoris.