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Biomedical subjects

Y Nara

Publications and source records attributed to Y Nara.

At least 271 records · Page 15Linked to original sources
PubMed1977

Depressant action of acetate upon the human cardiovascular system.

The effect of regular hemodialysis (HD) with dialyzate containing acetate was evaluated in 20 patients. After dialysis, a significant increase in limb blood flow was found (P less than 0.01) while the mean arterial blood pressure remained unchanged indicating a significant decrease in peripheral vascular resistance after HD (P less than 0.01). Cardiac function was evaluated using the ratio of the preejection period to left ventricular ejection time (PEP/ET); this value showed a significant increase after HD suggesting depression of cardiac function (P less than 0.001). The study was repeated substituting bicarbonate for acetate in 13 of the 20 patients. Under these conditions, limb blood flow and peripheral vascular resistance showed no significant change though mean arterial blood pressure decreased significantly (P less than 0.01). The ratio, PEP/ET, showed a significant increase after HD (P less than 0.01), but the value was significantly lower than that found after HD with dialyzate containing acetate (P less than 0.05). Changes in the serum levels of calcium, potassium, pH and body weight could not explain the differences found after HD with the two kinds of dialyzate. The results of the present study suggest strongly that acetate exerts a depressant action on the cardio-vascular system.

Acetates↗
PubMed1976

Importance of hypertension and genetic factors for atherogenesis in rats.

1. A new experimental system has been used to analyse factors involved in the initiation of atherosclerosis in rats. 2. Arterial fat deposition in the cerebral arteries was affected by blood pressure, serum cholesterol concentrations, strain difference and age, of which high blood pressure was the most important. 3. A genetic factor independent of hypertension was shown to be involved in acute arterial fat deposition in spontaneously hypertensive rats.

Age Factors↗
PubMed1976

Vectorcardiographic study on left ventricular hypertrophy in spontaneously hypertensive rats.

To observe cardiac changes in spontaneously hypertensive rats (SHR) functionally, the vectrocardiographic approach was tried, applying the Takayasu lead system to rats. This vectrocardiogram (VCG) was shown to be sufficiently good to detect left ventricular hypertrophy (LVH) in SHR. VCG in SHR showed specific features, some of which were left upward deviation of the maximum QRS vector in the frontal plane, an increased magnitude of the maximum spatial QRS vector, and prolongations of such indices as the QRS duration, time to the maximum spatial QRS vector and QT interval with abnormal ST-T changes. The P wave of SHR in the X scalar electrocardiogram, lower and wider than that of Wistar-Kyoto rats may also be a significant feature of LVH in SHR. The angle of the maximum QRS vector in the horizontal plane was not proven to be a suitable index of LVH in SHR. Most of the histometrical findings were closely correlated to blood pressure. Some of the vectrocardiographic findings were significantly correlated both to blood pressure and to some of the characteristic findings of LVH, such as the weights of the heart and the left ventricle and so forth. This experiment also indicated that LVH in SHR was not limited only to quantitative myocardial hypertrophy. It also seemed to be related to reversible or irreversible qualitative changes of coronary arteries or myocardium, such as myocardial fibrosis. This vectrocardiographic method was shown to be useful in obtaining various information about the cardiovascular system in rats, especially in SHR, and it seemed to be helpful for further understanding hypertensive cardiac diseases in humans.

Animals↗
PubMedDate not supplied

Effects of high-calorie diet on blood pressure and sodium retention in spontaneously hypertensive rats and normotensive Wistar-Kyoto rats.

Previous reports from our laboratory have documented that spontaneously hypertensive rats (SHR) have insulin resistance and that insulin resistance is enhanced by high-caloric diet (HCD) feeding. The aim of this study was to elucidate the effect of HCD on blood pressure and sodium retention in both SHR and normotensive Wistar-Kyoto rats (WKY). SHR and WKY were divided into two groups. One group of rats was fed normal diet (ND). The other rats were fed HCD. After the 8-week feeding period, insulin suppression tests were performed. The animals were individually housed in metabolic cages for the last 2 days of the experiment. Food consumption was recorded for 24 h, and a 24-h urine was collected to calculate the sodium excretory ratio. In both strains, body weight was significantly increased by HCD feeding. Blood pressure was significantly elevated in SHR by HCD feeding, whereas that of WKY was not affected by HCD feeding. In both strains, steady-state plasma glucose (SSPG) during the insulin suppression test was higher in the HCD group than in the ND group. SSPG was consistently higher in SHR than in WKY treated with HCD. Urinary sodium excretion ratio was significantly decreased in SHR by HCD, and plasma potassium concentrations were significantly lower in SHR with HCD than in SHR with ND, whereas those of WKY were not affected by HCD feeding. SHR are more sensitive to the induction of insulin resistance than WKY, resulting in sodium retention and elevation of blood pressure.

Animals↗
PubMedDate not supplied

Beneficial effects of fish oil on glucose metabolism in spontaneously hypertensive rats.

1. Increased interest in fish oil led us to examine their metabolic effects in spontaneously hypertensive rats, which have been reported to have glucose intolerance. 2. Rats were divided into three groups: (i) a control group fed standard rat laboratory chow; (ii) a lard group fed a high-fat diet containing 20% lard; and (iii) a fish oil group fed a high-fat diet containing 20% fish oil for 14 weeks. 3. Systolic blood pressure and fasting blood glucose were markedly increased in the lard group, whereas in the fish oil group they were only transiently increased at the beginning and decreased to levels seen in the control group. 4. Intraperitoneal glucose tolerance test demonstrated that fish oil reversed the impairment of glucose disposal found in the lard group. However, plasma insulin levels were raised transiently at 30 min in the fish oil group compared with the control group. 5. Insulin secretion from pancreatic islets stimulated with glucose in vitro was also enhanced by fish oil. 6. These results lead us to conclude that fish oil improves glucose tolerance by enhancing insulin secretion from pancreatic beta-cells.

Animals↗
PubMedDate not supplied

Effect of dietary urea on blood pressure in spontaneously hypertensive rats.

The feeding of a normal diet containing 13.5% urea (in place of protein in a high protein diet) attenuated the development of severe hypertension and decreased the incidence of stroke in spontaneously hypertensive rats (SHR), when 1% NaCl solution was given to them. The urea not only increased urine volume, but also increased urinary sodium excretion in SHR given 1% NaCl for drinking. Although there was no obvious difference in erythrocyte size between the urea and the control groups, there was a significant inverse correlation between plasma urea level and erythrocyte size. These results suggest that a high protein diet reduced blood pressure partly through the diuretic effect of urea, the common metabolite of various proteins.

Animals↗
PubMedDate not supplied

Sodium preference and excretion in spontaneously hypertensive rats on various diets.

Stroke-prone spontaneously hypertensive rats (SHRSP) and stroke-resistant SHR (SHRSR) exhibited an increased preference for a 2% NaCl solution, relative to water, in comparison with normotensive Wistar-Kyoto (WKY), but the preference was lost quickly in SHRSP with unbroken exposure. Neither a high protein diet (50% fish protein) nor a low protein diet (5% protein) changed the salt water preference in SHRSR and the former abolished the preference more quickly in SHRSP. The fish protein diet, however, increased the ratio of urinary sodium excretion to dietary sodium intake in the first three days of exposure to a high salt intake in all groups. Results from this experiment suggest that an increased dietary protein intake can facilitate sodium excretion and may possibly ameliorate the adverse effect of a high sodium diet.

Animals↗