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T Yanaga

Publications and source records attributed to T Yanaga.

At least 19 recordsLinked to original sources
PubMed1991

Clinical effects of nitrendipine on variant angina pectoris.

The clinical effects of nitrendipine, a new calcium antagonist, were investigated in a single-blind test on 21 patients with variant angina pectoris. The efficacy of the drug was evaluated on the basis of frequency of anginal attacks and Holter electrocardiographic findings during different treatment periods at doses of 10 mg once a day (period I) and 20 mg once a day (period II). The number of anginal attacks decreased significantly from a pretreatment level of 2.1 +/- 0.3 per day to 0.7 +/- 0.2 per day in treatment period I and 0.3 +/- 0.1 per day in treatment period II (p less than 0.01, p less than 0.001, respectively). The consumption of sublingual nitroglycerin tablets decreased significantly in both treatment periods in comparison with the observation period before treatment (p less than 0.01, p less than 0.001, respectively). In 20 patients with continuous ECG monitoring, the frequency of ST-segment elevation was 4.5 +/- 1.0 per day during the pretreatment period; it decreased significantly to 0.9 +/- 0.6 per day in treatment period I and 0.5 +/- 0.3 per day in treatment period II (p less than 0.01, p less than 0.001, respectively). The duration and the maximum magnitude of ST-segment elevation also improved significantly in both treatment periods. These results demonstrate the efficacy of nitrendipine in the treatment of variant angina at a single daily dose of 10 mg.

Angina Pectoris, Variant↗
PubMed1989

Frequency characteristics of the heart rate variability produced by Cheyne-Stokes respiration during 24-hr ambulatory electrocardiographic monitoring.

Spectral analysis of heart rates during 24-hr ambulatory electrocardiographic monitoring has been carried out to characterize the heart rate spectral components of Cheyne-Stokes respiration (CSR) by using fast Fourier transformation (FFT). Eight patients with congestive heart failure were selected for the study. FFT analyses have been performed for 614.4 sec. Out of the power spectrum, five parameters were extracted to characterize the CSR. The low peak frequencies in eight subjects were between 0.0179 Hz (56 sec) and 0.0081 Hz (123 sec). The algorithms used to detect CSR are the followings: (i) if the LFPA/ULFA ratios were above the absolute value of 1.0, and (ii) the LFPP/MLFP ratios were above the absolute values of 4.0, then the power spectrum is suggestive of CSR. We conclude that the automatic detection of CSR by heart rate spectral analysis during ambulatory ECG monitoring may afford a tool for the evaluation of the patients with congestive heart failure.

Aged↗
PubMed1989

Sarcolemmal Ca2+ transport activities in cardiac hypertrophy caused by pressure overload.

To examine Ca2+ transport activities in sarcolemmal membrane in cardiac hypertrophy caused by pressure overload, rats were subjected to aortic banding for 28 days. Heart-to-body weight ratio was increased by 46% in aortic-banded animals in comparison with the sham-operated rats. Ouabain-sensitive Na+-K+-ATPase activity in sarcolemma (SL) from hypertrophied hearts was not different from that in the control preparation. The initial rate of Na+-dependent Ca2+ uptake in SL vesicles from the hypertrophied hearts was stimulated by 53% compared with the control vesicles. ATP-dependent Ca2+ uptake and Ca2+-stimulated adenosinetriphosphatase (ATPase) activities in SL from hypertrophied hearts were increased by 35%. The number of Ca2+ channels estimated by [5-methyl-3H]nitrendipine binding was decreased by 33% in SL from hypertrophied hearts. Total and individual phospholipid contents in the hypertrophied heart preparations were not different from those in the control, except that phosphatidylcholine and phosphatidylethanolamine contents were significantly increased. Sarcolemmal preparations from hypertrophied hearts from the 22-wk-old spontaneously hypertensive rats exhibited changes in Na+-Ca2+ exchange and Ca2+-pump activities (similar to those observed in banded hearts), whereas the Na+-K+-ATPase activity decreased, [3H]nitrendipine binding increased, and phospholipid contents were not different. Thus, although differences were defined between two types of hypertrophy, these results suggest alterations in the sarcolemmal Ca2+ transport activities that may serve as an adaptive mechanism for the removal of Ca2+ from the myocardial cells during the development of cardiac hypertrophy.

Animals↗
PubMed1989

[Analysis of EEG, respiration, and ECG by 24-hour polygraphic study in a case of aortitis syndrome associated with epilepsy].

The relationships between electroencephalographic changes and cardio-respiratory responses were analysed by using 24 hour ambulatory simultaneous monitoring of EEG, respiration, ECG in a patient with aortitis syndrome. Circadian changes of "absence" attacks, effects of anti-convulsive drugs on epileptic attacks, and respiratory arrest and abnormalities of the cardiorespiratory integration were clarified.

Adult↗
PubMed1988

Modulation of Na+-Ca2+ exchange in cardiac sarcolemmal vesicles by Ca2+ antagonists.

The purpose of this study was to examine the effect of three classes of Ca2+ antagonists, diltiazem, verapamil and nifedipine on Na+-Ca2+ exchange mechanism in the sarcolemmal vesicles isolated from canine heart. Na+-Ca2+ exchange and Ca2+ pump (ATP-dependent Ca2+ uptake) activities were assessed using the Millipore filtration technique. Sarcolemmal vesicles used in this study are estimated to consist of several subpopulations wherein 23% are inside-out and 55% are right side-out sealed vesicles in orientation. The affect of each Ca2+ antagonist on the Na+ dependent Ca2+ uptake was studied in the total population of sarcolemmal vesicles, in which none of the agents depressed the initial rate of Ca2+ uptake until concentrations of 10 microM were incubated in the incubation medium. However, when sarcolemmal vesicles were preloaded with Ca2+ via ATP-dependent Ca2+ uptake, cellular Ca2+ influx was depressed only by verapamil (28%) at 1 microM in the efflux medium with 8 mM Na+. Furthermore, inhibition of Ca2+ efflux by verapamil was more pronounced in the presence of 16 mM Na+ in the efflux medium. The order of inhibition was verapamil greater than diltiazem greater than nifedipine. These results indicate that same forms of Ca2+-antagonist drugs may affect the Na+-Ca2+ exchange mechanism in the cardiac sarcolemmal vesicles and therefore we suggest this site of action may contribute to their effects on the myocardium.

Adenosine Triphosphate↗
PubMed1988

Effect of a new calcium antagonist, nilvadipine, on variant angina pectoris evaluated by 24-hour Holter electrocardiography.

The clinical effect of nilvadipine, a new calcium antagonist, was investigated in a single blind trial in 19 patients with variant angina pectoris. The efficacy of the drug was evaluated on the basis of frequency of anginal attacks and Holter electrocardiographic findings during observation periods and during two treatment periods when the drug was given in doses of 4 mg twice a day or 4 mg 3 times a day. The frequency of anginal attacks and the consumption of sublingual nitroglycerin tablets decreased significantly in both treatment periods in comparison with those in the observation period before treatment, but in the observation period after treatment tended to increase in comparison with those during the second treatment period. The frequency and duration of ST-segment elevation and the maximum ST-segment elevation confirmed by Holter electrocardiography also improved significantly in both treatment periods, compared with those in the observation period before treatment. Our findings show that nilvadipine is effective for variant angina pectoris at doses of 4 mg twice a day.

Angina Pectoris, Variant↗
PubMed1986

Role of the suprachiasmatic nuclei of the hypothalamus on diurnal rhythm in cardiac arrhythmias.

Ambulatory EGG and EEG recordings were recorded under a 14/10-h light-dark illumination schedule using rats. The rats consisted of two groups: a suprachiasmatic (Sch) lesioned group (n = 5) and a normal control group (n = 5). Bilateral Sch nuclei were lesioned electrically (DC, 2.5 mA, 30 s for each) using a pair of platinum electrodes 0.3 mm in diameter. After recovery from surgery, recordings of ECGs (leads I, II, and III) and EEGs from the cortex and the left dorsal hippocampus were continued for 6 days. Diurnal periodicity in bradyarrhythmia (sinoatrial block, atrioventricular block) and heart rate was analyzed by the least square fit of 24-h cosines. Significant diurnal rhythm was observed in control rats, whereas Sch-lesioned rats showed no significant diurnal rhythm. The integrity of the Sch nuclei, therefore, is necessary for the generation and/or the expression of diurnal periodicity in bradyarrhythmia in rats.

Animals↗
PubMed1984

[Pituitary hormone responses to exercise at high altitudes].

The secretory responses of the anterior pituitary hormone to physiological stress were studied in healthy male volunteers. Measurements of blood LH, FSH, Prolactin, GH, ACTH, lactate, pyruvate and hematocrit were made from blood samples taken at rest, after 15 minutes at sea level, and at an altitude of 4000 m and 5500 m modulated in a climate-controlled room. The results are summarized as follows: Blood levels of Prolactin and ACTH were increased after exercise at a high altitude. Blood levels of LH and FSH after exercise at each altitude were not significantly different from those at rest. Blood GH level was increased after exercise at any altitude. Blood levels of lactate and pyruvate were increased after exercise at any altitude. These results suggest that the secretory response of the anterior pituitary hormone to physiological stress is prominent in Prolactin, GH and ACTH but not in FSH and LH.

Adrenocorticotropic Hormone↗
PubMed1984

Influence of glucocorticoids on brain serotonin metabolism in rats.

It has been suggested brain serotonin (5HT) plays a role in regulation of the hypothalamic-pituitary-adrenal system, although none of the experimental approaches so far reported has produced unequivocal results, mainly on account of the static tissue 5HT level or the known effects of drugs being employed in interpretation of their data. The present study in rats of the possible feedback influence of glucocorticoids on the brain 5HT was designed to analyze the dynamic turnover of its metabolism. Intracisternal injection of corticosterone (COR) caused no significant changes in 5HT content but increased its turnover dose-dependently in the cortex-cerebellum and the rostral brain stem including the hypothalamus, and lowered the serum COR level at doses less than 5.0 micrograms/kg, reducing its effect with increasing doses. Intracisternal or intraperitoneal administration of miliary doses of dexamethasone (DEX) decreased 5HT turnover in the same brain portions. The effects of glucocorticoids on the brain 5HT metabolism were more potent when injected intracisternally, especially onto the rostral brain stem. Although COR and DEX played controversial roles, the present results suggest that adrenal glucocorticoids may directly act on brain 5HT metabolism and there may be a feed-back relation between adrenal glucocorticoid and brain 5HT.

Animals↗