We have established a simplified assay system for the measurement of urinary kallikrein activity by utilizing the sensitive and specific radioimmunoassay system of kinins previously reported from our laboratory. Kinins were generated by incubating urine samples (50μl) with kininogen (1500 ng) in the presence of kininase inhibitors, and the generated kinins were measured by radioimmunoassay. Since the cross reactivity of kininogen in the kinin radioimmunoassay system was not recognized at dose up to 1.0 μg, the amount of untreated kininogen in the radioimmunoassayed samples did not interfere with the measurement of kinins. This eliminated the necessity for a kininogen extraction procedure. A good linear correlation (r=0.939, p<0.001) was observed between the urinary kallikrein activity determined by this assay system (kininogenase activity) and that by esterolytic activity. Urinary kallikrein activity was 3.3 ± 0.9 μg/min/24hour urine (mean ± SEM), 1.4 ± 0.4 μg/min/24hour urine and 0.25 ± 0.06 μg/min/24hour urine in 6 normal subjects, 7 patients with non-complicated essential hypertension and 4 patients with chronic renal failure, respectively. Thus, urinary kallikrein activity was significantly lower in the patients with essential hypertension (p<0.05) and the patients with chronic renal failure (p <0.01) than the normal subjects.

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A critical comparison of radiocardiograms with ^99mTc-and ¹³¹I-albumins was made to determine whether or not ^99mTc-albumin can be used as a tracer for measuring blood volume (BV) and cardiac output (CO). Simultaneous injection of both isotopes was given to twenty-two patients to obtain radiocardiograms for each by means of a single scintillation counter with two pulse height analyzers. Such method allows for the determination of the energy levels for both ^99mTc and ¹³¹I. The radiocardiographic pattern was somewhat different between ^99mTc-and ¹³¹I-radiocardiograms : The ratio of left to right peak height was 16% on the average lower in the ^99mTc-radiocardiogram than in the ¹³¹I-one. The reason for the lower ratio is explained by greater absorption of ^99mTc-radioactivity within the soft tissue interposing between the scintillation probe and heart. The values for ^99mTc-derived blood volume were 7.4% on the average larger than those for ¹³¹I-derived blood volume (p less than 0.01), although the correlation was excellent (r= 0.98, p less than 0.01). There was no systemic difference between cardiac output determined by ^99mTc- and ¹³¹I-albumins since the overestimation of blood volume can compensate for the underestimation of CO/BV by ^99mTc-study. In view of its rapid extravasation, ^99mTc-albumin is not so appropriate tracer for accurate measurements of BV and CO/BV, although it may be used for measurement of cardiac output.

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Several different exercise testings with treadmill, bicycle ergometer and two-step were carried out by healthy Japanese men to study oxygen consumption per minute and circulatory responses. Stress imposed on the heart by dynamic leg exercise varied depending on the mode of exercise even if energy expenditure expressed in V^^·O₂ was identical. This should be fully taken into consideration in comparison of results of different modes of exercise testings. For estimation of V^^·O₂ during treadmill slope walk, an equation was derived by multiple regression analysis with use of belt speed and slope as independent variables.

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We performed exercise stress scintigraphy with thallium-201 in 88 patients including 31 patients of effort angina and nine patients of old myocardial infarction without angina. Sensitivity of exercise stress scintigraphy to detect effort angina was 77%, whereas sensitivity of exercise stress ECG was only 44.5%. The combination of stress scintigraphy with stress ECG enhanced sensitivity up to 87%. Exercise stress scintigraphy was useful particularly in cases with one vessel disease and those who failed to achieve sufficient exercise stress. Besides exercise stress scintigraphy did not show false positive response, differing from exercise stress ECG. Myocardial imaging is a method which shows the balance between myocardial perfusion demand and supply.

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Changes in ET/PEP in normal subjects are characterized by initial increase associated with the increase in the heart rate, stroke volume and cardiac contractility and are subsequently followed by plateauing or slightly decrease after exceeding the 70% heart rate level of the age predicted maximal heart rate. The decrease in ET/PEP is thought to be mainly due to decrease in stroke volume. After exceeding the predicted maximal heart rate, ET/PEP reveals remarkable decrease that may reflect decreased cardiac function (CF). Some patients with ischemic heart diseases revealed decrease of ET/PEP at the heart rate less than the 60% level of the age predicted maximal heart rate. This may indicate decreased cardiac contractility associated with decreased stroke volume (Fig. 10) Since transient left ventricular failure is thought to take place in anginal attack^12-14, decreased ET/PEP at the heart rate below the 60% of age predicted maximal heart rate may indicate decreased cardiac function, although invasive evaluation of the cardiac function was not performed in the present study.

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1. Impedance cardiography proved valuable to estimate the stroke volume and other cardiac parameters noninvasively, when the electrical resistivity of the blood was corrected with hematocrit. 2. Cardiac response to graded exercise on a bicycle ergometer up to the maximal load in healthy young and active middle-aged subjects was divided into four phases from the changes in cardiac parameters such as stroke volume, cardiac output, ejection index and height of the atrial wave. 3. The ischemic patients did not tolerate well the exercise after the second phase or drift phase of exercise. 4. Physical training enhanced the cardiac function in work through increase in cardiac output and work load.

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Eleven cases with angina of effort and 6 cases with giant negative T wave were subjected to bicycle test in the sitting position to assess the hemodynamic changes as compared with those in 6 control cases. Measurements were made of the mean pulmonary capillary wedge pressure (m-PCP≒LVEDP) as a parameter of left ventricular function and ST segment depression in the electrocardiogram during exercise every minute. In control group, m-PCP increased 3 mmHg (Δm-PCP= 2-4 mmHg) on average, observing a constant value of m-PCP during exercise. In all cases of angina, chest pain was elicited during exercise where there was a progressing increase in m-PCP with a significant difference from control group (p <0.05). In 7 cases of angina, the PCP-LVSWI relationship demonstrated impairment of left ventricular function due to myocardial ischemia. In cases of two or three vessel disease, the increase in m-PCP during exercise was coincident with the onset of ST segment depression in the exercise ECG. There was a high-grade correlationship between the increment in m-PCP and the magnitude of ST segment depression (r= 0.87-0.99). A close correlationship also existed between the magnitude of ST segment depression and the rate-pressure product (r=0.88-0.99). This suggests that the magnitude of ischemic ST segment depression reflects the severity of myocardial ischemia and is also closely related with impaired left ventricular function due to the reduction of contractility and compliance of the heart. The cases of giant negative T wave proved to have a normal pumping function without coronary artery lesions. The increase in m-PCP during exercise was more marked in 5 of 6 these cases than in control group (m-PCP= 5-9 mmHg), probable because of decreased left ventricular compliance due to atypical hypertrophy. The blood pressure during exercise in this group was significantly higher (p<0.05) than in control group, leading to a part of cause for atypical hypertrophy.

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(1) Exercise test was a simple method for differentiating physiological and pathological bradyarrhythmia. (2) Exercise test was useful for functional evaluation of the sinus node activity in SSS and of AV conduction in AVB, and for the determination of the site of subsidiary pace-maker in CHB. (3) Exercise test was of clinical significance for determining the indication of artificial pace-maker implantation in cases with bradyarrhyarrhythmias.

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