Preoperative and one-month postoperative Frank vectorcardiograms were recorded on 44 patients with mitral stenosis, which were divided into four groups according to their preoperative mean pulmonary pressures. In the group with absent pulmonary hypertension, the leftward components of the 0.04-second and the maximum QRS vectors were significantly increased postoperatively. In the group with minimal pulmonary hypertension, the leftward components of the 0.03-, 0.04-second and maximum QRS vectors and the maximum leftward component were significantly increased post-operatively. In these two groups, however, the postoperative QRS loops in the horizontal plane were about the same in configuration as the preoperative ones. Therefore, it was noted that the quantitative analyses of instantaneous vectors rather than mere morphologic comparisons of QRS loops were necessary to demonstrate the relatively small postoperative changes that occurred in the two groups. In the group with moderate pulmonary hypertension, the preoperative horizontal loops showing evidence of RVH made marked changes to the direction of normality postoperatively. The maximum posterior component was significantly decreased postoperatively. The leftward components of the 0.02-, 0.03-, 0.04-second and maximum QRS vectors and the maximum leftward component were significantly increased postoperatively. In the group with severe pulmonary hypertension, the postoperative loops in the horizontal plane still showed evidence of RVH, though the degree of RVH was much less severe in comparison with that of the preoperative ones. The postoperative increase in the maximum leftward component, the postoperative decrease both in the maximum right-ward component and the maximum posterior component were all significant. The leftward components of the 0.03-, 0.04-second and maximum QRS vectors were markedly increased postoperatively.

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Spontaneously hypertensive rats (SHR) developed and maintained hypertension in spite of low sodium intake. The development of hypertension was accelerated and hypertension was enhanced by chronic excess sodium intake (1% salt in drinking water with or without high sodium diet). Various sub-strains of SHR showed some difference in sensitivity to salt ingestion. Consequently, hypertension in SHR is mainly determined by genetic factors, the minor part of which interacts with excess salt intake especially in several substrains of SHR.

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556The feasiblity of operation on a patient with widespread coronary artery disease was described. The patient in this report was failing in spite of competent medical therapy and was considered from following of ECG findings as a progressive cornary artery disease. His obstructive disease was rather severe and the arteriographic findings clearly indicated the widespread diffused occlusive disease of the left coronary artery. Bilateral internal mammary artery implantation was performed with a median strenotomy. During the period of between the postoperative third and tenth months, the patient had markedly symptomatic improvement and his anginal attacks were gradually disappeared. ECG findings in the sixth month after operation revealed significant improvement of coronary insufficiency. Cineangiographic evaluation per-formed 10 months postoperatively revealed both implanted internal mammary arteries to be patent, and demonstrated new anastomotic channels between the implants and diseased coronary arteries. The case reported clearly demonstrates that bilateral internal mammary artery implantation can contribute large quantities of arterial blood to the coronary arterial system of a patient with widespread diffused coronary artery disease.

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Genetic factors involved in spontaneous hypertension were analyzed in the F₂ generation obtained between spontaneously hypertensive and normotensive rats. Positive correlations to blood pressure were observed in the heart, pituitary and adrenal weights, and in the thyroidal acid phosphatase activity. A weak inverse correlation was observed between blood pressure and aroma-tic L-amino acid decarboxylase activity of the brainstem. The F₂ with the hypertensive pattern of renal esterase isozymes showed a significantly higher blood pressure than the F₂ with the normotensive pattern. These findings correlated to blood pressure may be related to the genetic pathogenesis of spontaneous hypertension except for the secondary effect of hypertension.

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In this study, evidence was established that the arterial contractile protein extracted by us must be arterial natural actomyosin and its characteristic features were clarified. Replacement of KCl by NaCl in the medium was inclined to enhance the superprecipitation and the ATP-ase activity of arterial natural actomyosin and then the de-crease of NaCl concentration in the perfusate resulted in reduction of the contractility of arterial strip by vasoactive agents. These results may explain clinical and epidemiological finding that a high intake of NaCl leads to hypertension.

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Angiotensin I converting enzyme was partially purified from' rabbit plasma and from the lung. We failed in our efforts to separate converting enzyme from kininase activity using column chromatography, gel filtration, electrophoresis and inhibitor.

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Sympathetic nerve activities in chloralose-anesthetized dogs were recorded directly during infusions of angiotensin into vertebral artery and femoral vein. 1. With vertebral artery infusion of angiotensin arterial pressure increased to 27 ± 11.1 mmHg and pressure rising began 20 ± 6.6 seconds after starting the infusion. Intravenous infusion of the same doses of angiotensin induced arterial pres-sure rise of 10 ± 6.6 mmHg and its onset was 68 ± 29.8 seconds. 2. Rise in arterial pressure was associated with initial augmentation of nerve activity in splanchnic and renal nerves. Cardiac nerve activity was not increased. 3. During arterial pressure was maintained at a higher level, a characteristic change in nerve activity was that rhythmical discharges in renal nerve activity disappeared completely and small non-rhythmical activity occurred instead, while the large bursts of discharges in splanchnic nerve activity never disappeared. 4. The pressor response to angiotensin was inhibited by pretreatment with guanethidine, but not with atropin. The results suggest that angiotensin acts on central nervous system to increase central sympathetic outflow in splanchnic nerves, resulting in a rise in arterial pressure.

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The mechanism of estrogen hypertension was studied in rats. After the administration of 0.2 mg of estriol and 2 mg of stilbestrol disulfate for 14 days, three of 10 rats have developed hypertension. However, in the rats with the same amount of estrogen and salt loading (1% NaCl as drinking solution), only 1 of 10 has developed hypertension. Renin substrate increased significantly in both the groups, but serum renin activity, serum renin concentration and renal renin content in estrogen treated rats were significantly higher than those in the rats with the combination of estrogen and salt loading. In addition, the rats in which hypertension has developed showed higher values of renin activity, renin concentration and renal renin content compared to those in the rats which remained normotensive. Therefore it seems to be possible to think that renin release and the rate of angiotensin formation with the high level of renin substrate play an important role in the development of estrogen hypertension. Furthermore, this study suggested that it might be possible to prevent estrogen hypertension by suppressing renin release completely.

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The epicardial coronary arteries of the aged hearts are often found to be rigid, tortuous and calcified. There have been many reports about the buckling of the great vessels (e.g. thoracic or abdominal aorta, innominate artery, carotid artery etc.), but there have as yet been few reports which have concerned with the tortuosity of coronary arteries of the aged. A considerable number of publications about coronary calcifications of the white person and the Negro have been described, while little is known about coronary calcifications of the Japanese. In order to study the incidence and characteristics of tortuous, calcified coronary arteries in the aged, postmortem coronary arteriographic investigation was made of 82 hearts using new contrast medium. Materials and Methods: Materials; The hearts included in the present angiographic study were obtained from 82 non-selected autopsies at the Yofuen (Old People's Home) and the Kanazawa University Hospital. The ages of the patients ranged from 22 to 91 years. Fourteen patients were less than 60 years of age, 16 patients between 60 and 69 years of age, 23 patients between 70 and 79 years of age and 29 patients were over 80 years old. The ratio of males to females was approximately 1 to 1.5. Angiographic techniques; The hearts were freshly removed from the pericardial sac. The aorta was transected immediately above the aortic valves, then the proximal one to two cm of each coronary artery was dissected free of surrounding connective tissue. After the two cannulas have been tied in place, an anteroposterior roentogenogram of the specimen was obtained. Under X-ray monitoring, the right coronary artery was first injected with contrast medium, then anteroposterior and lateral roentogenograms were obtained. Next, the left coronary artery was injected and roentogenograms were obtained as in the case of right coronary artery. Roentogenograms were obtained with 45 (±1) kilovolts, 100 milliamperes and 4/100 second at 100cm distance. The radiopaque medium used was 76 per cent Urografin with a viscosity of 16.5 cps at 20°C.

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