The effect of propranolol on some ECG abnormalities induced by different kinds of the phenothiazine was investigated in 5 psychiatric patients. The ECG changes such as sinus tachycardia, depression of ST-segment and flattening of T-wave could be reverted toward normal with propranolol. This suggests that the drug is effective in preventing such undesirable effect of the phenothiazine on the heart. Theoretical importance of the favorable action of propranolol on these abnormal ECG's was discussed.

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The transformation, rising pressure, isovolumic and ejection periods of the right heart were determined by analysis of a pulmonary arterial pressure wave recorded during cardiac catheterization in man. These easily and accurately determined periods are useful in the study on cardiac dynamics of the right ventricle in man.

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The effects of sympathetic nerves and catecholamines on the characteristics of the myocardial reactive hyperemia were studied in anesthetized open-chest dogs. The flow repayment, the ratio of the reactive hyperemic blood flow to the flow debt, averaged 166 per cent. The calculated oxygen debt was also overpaid, the average repayment being of 118 per cent. The occlusion of the left coronary artery up to 40 sec. did not affect the flow repayment; a constant correlation was observed between flow debt and reactive hyperemic flow. To study the sympathetic effect on the reactive hyperemia characteristics, acute cardiac sympathectomy, intracoronary infusion of propranolol and deprivation of catecholamines by reserpinization were performed. These procedures did not affect the repayment of flow and oxygen debt. From these experimental results the sympathetic nervous control was not observed in the response of the myocardial reactive hyperemia indicating that reactive hyperemia was primarily a metabolic response induced by anoxia. It was also suggested that catecholamines in the heart did not play any significant metabolic role in the regulation of the myocaridal reactive hyperemia.

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Myocardial metabolism in reactive hyperemia was studied in anesthetized open-chest dogs. To produce reactive hyperemia the cessation of left coronary blood flow was carried out for 20 sec. During reactive hyperemia the myocardial extraction of glucose did not change significantly, but that of lactate was slightly decreased. On the other hand the. marked increase in the myocardial extraction of FFA was demonstrated during reactive hyperemia. The concentration of pyruvate in coronary sinus blood elevated over the control level 20 to 40 sec after the release of coronary occlusion and returned to the control level in two or three minutes. However the concentration of lactate revealed little change in this period. The increase in the myocardial oxygen consumption was remarkable in the first 20 sec after the release and calculated oxygen debt was already repaid in this period. These results confirmed that the anoxic metabolism in myocardium returned to the control level in a very short time during reactive hyperemia. A possible role of FFA in the mechanism of reactive hyperemia was indicated.

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Extrasystoles with a fully compensated pause were experimentally induced in dogs for analysis of their effects on myocardial contractility and hemodynam-ics. The first postextrasystolic beat showed improved hemodynamic measurements exceeding the respective values of the pre-extrasystolic beat of the basic rhythm, making some compensation for extrasystole-induced depression of hemodynamics, which was progressively enhanced as the coupling time be-came shorter. The coupling time, the site of origin, and even the frequency of the extrasystole did not affect the rate of compensation, which averaged 60%. It was confirmed that hemodynamics in extrasystoles was mainly affected by two independent factors; the blood volume in the ventricle at the onset of ventricular contraction with the resultant STARLING'S effect, and ventricular contractility for individual beats, the latter of which depends upon myocardial contractility and the sequence of ventricular contraction. Postextrasystolic potentiation was regarded as the positive inotropic effect of the premature activation on the myocardium in postextrasystolic beats.

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For myocardial tissue blood flow measurements, the flexible and thread-like cross thermocouple probes were implanted into the interior of the left ventricular wall, and the regional distribution of the blood flow and the generation mechanisms for the blood flow wave were examined. Methods 1. Preparation Mongrel dogs weighing from 17 to 25kg were anesthetized with pentobarbital sodium, 35 to 45 mg/kg, i.v. The arterial Po₂ was maintained to normal level by a Bird's respirator. The chest was opened by resecting the first to 8th ribs of the left side. After pericardiectomy, the cross thermocouple probes were implanted into the interior of the anterior aspect of the left ventricle to settle the two junctions of the probes nearly in the same distance from either the epicardium or endocardium. Then, the straingauge bridges were sewn onto the adjacent area for tension measure-production and heat or temperature conductivity ments. A monopolar electrode for e.k.g. was also attached to the wall close to the probes. There-after, the probes of electromagnetic flowmeter were set on the ascending aorta, pulmonary artery, anterior descending branch and circumflex branch of the left coronary artery and to the coronary vein (Fig. 2). 2. Cross Thermocouple Probes (Fig.1 and 3) The probes for heat clearance method are made of copper and constantan threads 100μ in diameter. The distance between the heated junction (D in Fig.1) and the reference one (E) is from 4 to 5mm. The heated junction was heated by 50 mA. AC to maintain its temperature about 3°C above that of the tissue. A spine about 100μ in length was attached to the heated junction to prevent slipping of it during myocardial contraction (Fig. l). a) A temperature gradient of 1°C between the junctions generates 42μV of the thermoelectromotive force. b) The maximum collecting distance (or axial temperature field) in the myocardium is 3.5mm. c) The response time of the probes is from 1 to 3 msec.

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Continuously measuring the myocardial tissue blood flow by heat clearance method using the cross-thermocouple probes whose character has been described elsewhere, the roles, in the regulation of the flow, of the sympathetic nerve, vagal nerve, carotid sinus and the sympathetic afferent fibers with the receptor sites in the thoracic cavity were examined in the anesthetized dogs with the results that their role varied considerably by the layers of the left ventricular wall. In this paper, the differences between the nervous control of the coronary blood flow and that of the tissue blood flow and those between the nervous control of the blood flow in the inner layer and that in the outer layer were represented and the possible mechanisms for the differences were discussed. Method s Experiments were carried out on the mongrel dogs, weighing from 18 to 25 kg, anesthetized with pentobarbital sodium (35-45 mg/kg, I.V.). The arterial Po₂ was maintained to normal level by a Bird's respirator. The thoracic cavity was opened by resecting the ribs from the first to 8th on the left side. After pericardiectomy, the anterior descending branch of the left coronary artery proximal to its origin was carefully separated from the surrounding connective tissues not to damage the nerves which run close to it. Thereafter, a probe of electromagnetic flow-meter was set on it. In order to measure the myocardial tissue blood flow, a pair of the thermoprobes were implanted into the interior of the left ventricular wall. The two thermojunctions of the probes were settled nearly in the same distance from either the epicardium or endocardium to avoid the influence on the thermoelectromotive force of the temperature gradients, different heat production and different heat or temperature conductivity in the wall. Thereafter, the strain-gauge bridges for tension measurements were sewn onto the wall adjacent to the probes. In addition, a monopolar electrode for e.k.g. was attached to the wall close to the probes. The left stellate ganglion was freed from the surroundings. After transsecting the branches of the central side, the ganglion was placed across a pair of platinum-ilidium stimulating electrodes. The right cervical vagus was prepared in the same way for electrical stimulation. The nerves were stimulated with the electric pulses of 0.5 msec duration, square wave, 12 V, and of 10 cps. The stimulus frequency was altered when necessary from 0.5 up to 10 cps.

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We have performed a clinical observation on ar-teriosclerosis for the recent several years, analyz-ing the serum lipids and classifying lipemia into several categories according to the serum choles-terol and triglyceride levels. Examining the dis-tributions of ischemic heart patients and non-ischemic control subjects in every category, it was found that the classification by both the cho-lesterol and triglyceride levels was more signifi-cant than that by either cholesterol or triglyceride level. This time, on the basis of such findings, classified lipemia depending on both the levels, and the characteristics of the lipemia were studied from some aspects in the category where the distribution of ischemic heart patients was distinctly higher than that of non-ischemic control subjects. Material and Methods Male and female subjects with various diseases, aged 40 years or more, hospitalized in our medical ward and selected at random, were employed in the present study, excluding the subjects with such diseases to be apt to accompany serum lipid disorder as renal diseases, diabetes mellitus, endo-crinological and hepatobiliary disorders. The subjects were kept on the diet containing 80g of proteins, 45g of fats, 400g of carbohydrates, and total calories of 2300-2500 Cal. per day. The fasting blood samples were collected in the early morning 12 hours or more after the last meal. No drugs which significantly influence on serum lipids were administered during the experiments. The diagnosis of ischemic heart disease was made by the observation on the ST segments and T waves on electrocardiogram following the Minnesota code. 1. In 173 subjects with ischemic heart and 337 non-ischemic control subjects, total 510 subjects, the serum cholesterol and triglyceride concentrations were measured and, depending on the levels, these subjects were divided into the following four categories: Serum cholesterol concentration was estimated by ZURKOWSKI's method with little modification, and serum triglyceride concentration by LAURELL's method.

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With respect to the mechanism of formation of ST-T wave in the electrocardiogram, various hypotheses have been proposed by many investigators. However, it cannot be said that any of these has been entirely accepted. The author assumed that the formation of ST-T wave would be attributable to temporal and spacial difference in the electrical current occur-red in various parts of the ventricle. Such a differ-ence may be observed between the epicardial and endocardial sites. From this point of view, the following investigations on the repolarization phase of transmembrane action potentials of the endocardial and epicardial sites were performed. Method Ventricular muscle of the rabbit was subjected to the experiment. The preparation was perfused constantly flowing with oxygenated Tyrode solution at a constant temperature (37°C). The transmembrane action potential (AP) is recorded through a microelectrode of Ling-Gerad type filled with 3M KCl (resistance 20-30 MΩ). The driving stimuli were delivered through a monopolar silver wire electrode attached to the ven-tricular surface. In some experiments, two microelectrodes were concurrently inserted into the epicardium and endocardium. Monopolar surface electrogram was also simultaneously recorded. Results 1. Comparison of action potential configurations between the endocardial and epicardial sites As indicated in Fig. 1 and Table I, no significant difference was recognized in action potential amplitude as well as resting potential between the epicardial and endocardial sites, while significant difference was observed in duration of AP between the epicardial and endocardial sites (Table II). The mean value of the maximum rate of rise recorded from the epicardial and endocardial sites were 217.6 ± 60.4 volt/sec and 508.5 ± 86.1 volt/sec, respectively, the latter being significantly greater than the former (Fig. 2. Table III). 2. Effects of stimulus frequency on the epicardial and endocardial APs Effect of change in frequency of electrical stimulation on the AP of the endocardial and epicardial sites was observed (Fig. 3). At a higher rate of stimulation, the duration of the AP was markedly reduced and the amplitude of resting and action potentials slightly decreased. At a lower rate, the duration was prolonged while the amplitude of resting and action potentials was slightly decreased. A linear relationship was observed between the duration of the AP and stimulus frequency, the frequency ranging from 0.2 cps to 6 cps. The patterns of change in the AP by frequency change were virtually identical between the endocardial and epicardial sites.

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