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Biomedical subjects

Y Kakuta

Publications and source records attributed to Y Kakuta.

At least 91 records · Page 5Linked to original sources
PubMed1986

Acute effects of ibopamine hydrochloride on hemodynamics, plasma catecholamine levels, renin activity, aldosterone, metabolism and blood gas in patients with severe congestive heart failure.

Acute effects of 200 mg of orally given 4-[2-(methylamino)ethyl]-o-phenylene diisobutyrate hydrochloride (ibopamine hydrochloride) which is a new diisobutyric ester of N-methyldopamine, on hemodynamics and metabolism were evaluated in 11 patients with severe heart failure (New York Heart Association class IV). Significant effects occurred within 30 min and persisted for 6 h after dosing. Peak effects were observed at 2 h. At peak effects, cardiac index increased from 2.53 to 3.07 l/min/m2 (+20%, p less than 0.01), stroke volume index from 35 to 41 ml/beat/m2 (+18%, p less than 0.05), stroke work index from 35 to 44 g X m/beat/m2 (+26%, p less than 0.05), epinephrine from 0.05 to 0.15 ng/ml (+200%, p less than 0.05), urine volume from 50 to 81 ml/h (+61%, p less than 0.05), pulmonary capillary wedge pressure decreased from 23 to 18 mmHg (-24%, p less than 0.001), mean pulmonary arterial pressure from 33 to 27 mmHg (-19%, p less than 0.001), right atrial pressure from 10 to 7 mmHg (-27%, p less than 0.001), systemic vascular resistance from 1735 to 1546 dyne X s X cm-5 (-11%, p less than 0.1), pulmonary vascular resistance from 204 to 168 dyne X s X cm-5 (-25%, p less than 0.05), arterio-venous oxygen difference from 6.09 to 5.36 ml/dl (-12%, p less than 0.05), norepinephrine from 0.45 to 0.34 ng/ml (-24%, p less than 0.1), renin activity 1.80 to 1.26 ng/ml/h (-30%, p less than 0.05), respectively, whereas there were no significant changes in blood gases, heart rate, blood pressure, double product, aldosterone, urine Na+, K+ or lactate/pyruvate.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1985

Effect of Ca2+ on the ciliary beat frequency of skinned dog tracheal epithelium.

Beat frequency of dog tracheal ciliated epithelium was measured using a profile projector and a photomultiplier. The preparation, treated with 50 micrograms/ml of saponin for 15 min, lost osmotic behavior and the ciliary beat came to depend on externally applied MgATP2- indicating that ciliated epithelium is skinned with saponin. Beat frequency of skinned cilia did not increase with Ca2+ in 0.1 mM MgATP2- with no ATP-regenerating system. Under 4 mM Mg ATP2- the beat frequency increased with an increase in Ca2+ from 0.3 to 10 microM, although a marked beat continued in the virtual absence of Ca2+ sensitivity and maximum beat frequency increased with the addition of 2.4 microM calmodulin. The effect of calmodulin inhibitor (W-7) on skinned preparations was somewhat weaker than that on intact ones. We concluded that Ca2+, within the physiological range of concentrations, directly activated the ciliary proteins and increased the ciliary beat frequency. The addition of calmodulin augments the effect of Ca2+ but the basal beat frequency is not Ca2+ dependent.

Adenosine Triphosphate↗
PubMed1985

[Left ventricular wall motion in ischemic heart disease quantitatively assessed by three-dimensional vectors of reference points in multi-directional two-dimensional echocardiography].

Left ventricular wall motion was analyzed in a spatial geometric manner assuming the quantitative vectors formed by the reference points' movement on two-dimensional echocardiogram in 58 normal subjects and 40 patients with ischemic heart disease. Long-axis, RAO-equivalent and short-axis views, termed sagittal, frontal, and horizontal planes, respectively, were visualized and two or three reference points were defined on each plane. The vectors of these points' movement were obtained from video-image tracings on each plane and systolic excursion and distortion angles of each pair of reference points were vectorially assessed. All vectors in myocardial infarction were directed towards the infarcted areas. Clockwise horizontal distortion of the left ventricle apex-to-base axis was observed in normal subjects, but it was slight (3.1 +/- 3.0 degrees: mean +/- SD at the papillary muscle horizontal section). However, larger horizontal distortion was observed in single coronary artery disease, which may lead to the erroneous segmental wall motion analysis using conventional cineangiography because of the overlap of the adjacent segments.

Adult↗
PubMed1984

Effects of ATP and related compounds on the Ca-induced Ca release mechanism of the Xenopus SR.

The effects of ATP and related compounds on the Ca2+ release mechanism of the sarcoplasmic reticulum (SR) was studied by using skinned skeletal muscle fibers of Xenopus laevis. ATP evoked marked Ca2+ release at very low level of Mg2+. beta, gamma-Methylene analogue of ATP was almost as effective as ATP, which suggests Ca2+ release evoked by ATP is elicited without ATP hydrolysis. ADP and AMP also evoked Ca2+ release from the SR, but the effect of them became gradually weaker than that of ATP as the number of phosphates decreased. CTP, UTP and ITP were less potent than ATP. Adenosine also evoked more effective Ca2+ release than inosine. The compounds with adenine base, therefore, seem to elicit more potent Ca2+ release than those which have the same number of phosphates but do not consist of adenine base. AMP and Ca2+ ion evoked Ca2+ release synergistically, and the Ca2+ release responses evoked by ATP and related compounds showed the same pharmacological characteristics as Ca-induced Ca release. So, these Ca2+ release responses are construed as the manifestation of the same mechanism as Ca-induced Ca release. Effective concentration range of ATP and the effect of pyrophosphate on Ca2+ release evoked by ATP suggest that neither the high affinity ATP catalytic site of (Ca2+ + Mg2+) ATPase of the SR nor the low affinity ATP binding site, reported by Dupont (1977), is implicated in the enhancement of these Ca2+ release responses from the SR.

Adenosine Monophosphate↗
PubMed1980

The effect of graded coronary flow reduction in the left anterior descending and septal arteries on left ventricular function in the canine heart.

WE quantitatively analyzed the effect of graded left anterior descending and septal coronary flow (LAD + septal flow) reduction on left ventricular function with a left ventricular end-diastolic pressure (LVEDP) of 6 mm Hg and 12 mm Hg. We used an isolated, ejecting, canine heart preparation ( n = 8), the coronary flow of which could be controlled independently of the aortic pressure. We kept the other hemodynamic variables - heart rate, left circumflex coronary flow, right coronary flow and aortic input impendance - constant within their normal physiologic range. We considered this reduction in LAD + septal flow to be analogous to that of the most frequent lesion in ischemic heart disease. There was no plateau in the left ventricular work caused by this reduction of the regional coronary flow. Therefore, the plateau commonly reported in previous studies may be partially a result of the compensatory elevation of LVEDP, which is necessary to maintain the left ventricular work.

Animals↗
PubMedDate not supplied

Control of a total artificial heart using mixed venous oxygen saturation.

We developed a control of the total artificial heart (TAH) using mixed venous oxygen saturation (SvO2). With this method, the TAH output was controlled by automatically adjusting drive parameters in response to changes in measured SvO2. The feasibility and validity of this method were evaluated in a series of treadmill exercise tests using a calf implanted with a pneumatic TAH. The cardiac output (CO) and SvO2 were measured with an ultrasonic flowmeter and an oximetric catheter, respectively. The calf performed graded exercise under a fixed drive control mode (fixed mode), in which the drive parameters were unchanged throughout the treadmill test, and under the SvO2 based control mode (SvO2 mode). The calf could go to Stage 6 in both modes, but the maximal oxygen consumption in the SvO2 mode was 1.5 times as large as that of the fixed mode. Compared with the fixed mode, CO was increased effectively in the SvO2 mode, and the capacity for exercise was augmented. When considering the relationship between oxygen consumption and oxygen delivery, it was revealed that the CO in the SvO2 mode responded more adequately to the recipient's oxygen demand than that in the fixed mode. We conclude that this SvO2 based control method is feasible and physiologically effective.

Animals↗
PubMedDate not supplied

Mixed venous oxygen saturation as a promising parameter for physiologic control of total artificial heart.

Mixed venous oxygen saturation (SvO2) has been proposed as one of the suitable parameters for physiologic control of a total artificial heart (TAH). To establish the practical application of SvO2, we investigated the response of cardiac output (CO) and SvO2 to step-loaded exercise. A normal calf was surgically equipped with an ultrasonic flowmeter probe and an oximetry catheter in the pulmonary artery to measure CO and SvO2, respectively. Three stage step treadmill exercise tests (1, 2, and 4 km/h) were performed three times. While CO increased from 8.9 L/min at preexercise level to 9.7, 10.2 and 11.4 L/min at 1, 2, and 4 km/h, respectively, SvO2 decreased from 59.6% to 56.8, 55.3, and 52.2%, respectively. There existed a linear correlation between the magnitude of changes in CO and SvO2. CO and SvO2 exhibited a similar course of change, expressing an inverted exponential curve. The time constant of SvO2 was from 19 to 35 seconds, whereas that of CO was from 21 to 39 seconds. We conclude that SvO2 changes in close association with CO during exercise and has good potential to be a parameter for physiologic control of a TAH, by reflecting the recipient's CO demand without conspicuous time delay.

Animals↗
PubMedDate not supplied

A case of subarachnoid hemorrhage with electrocardiographic and echocardiographic changes simulating transmural myocardial infarction.

A patient with subarachnoid hemorrhage who exhibited changes suggestive of myocardial infarction by electro- and echocardiography and underwent coronary angiography is reported. Echocardiography demonstrated marked hypokinesis in the left ventricular anterior wall to the septum. Since the possibility of concomitant myocardial infarction could not be excluded, coronary angiography was performed with cerebral angiography. No abnormalities were observed in the coronary arteries, and the myocardial damage was considered to be due to subarachnoid hemorrhage. Echocardiograms showed improvements in left ventricular wall motion within a short time after operation of the intracranial lesion.

Cerebral Angiography↗