Vectorcardiographic features in the young SHR.
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Biomedical subjects
Publications and source records attributed to Y Nara.
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Biomembrane characteristics in stroke-prone SHR (SHRSP) and stroke-resistant SHR (SHRSR) were examined using erythrocytes as a simplified model. When erythrocytes were exposed to osmotic stress in the process of the migration from a higher to a lower osmotic gradient by the coil planet centrifugation, erythrocytes from SHRSP were hemolyzed at a higher osmotic pressure than those from SHRSR. Such a difference in biomembrane characteristics may be useful for detecting a genetic disposition of stroke.
From these results, we can conclude that the developmental pattern of hypertension in the young age is genetically determined and closely related to the incidence of hemorrhage or infarction. These newly selected substrains of SHRSP with higher incidences of cerebral infarction (SP-2) or hemorrhage (SP-1) are regarded as the better models for studying the pathogenesis, treatment, and prevention of infarction or hemorrhage, respectively.
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Acute transient hypertension by norepinephrine was loaded to stroke-resistant (SHRSR), stroke-prone (SHRSP), and normotensive Wistar Kyoto (WK) rats. (SHRSP were most sensitive to norepinephrine in young pre-hypertensive group.) Its effects on cerebral small vessels were studied using Evans Blue to detect the increase of vascular permeability. Severe macroscopic dye-leakages were observed in the areas of "recurrent branching" and "boundary zone", especially among young SHRSP, while SHRSR seemed to be least prone to dye-leakage both in young and adult groups. Among the adults, there was little difference between SHRSP and WK, probably because of the adaptive structural changes of arterial walls in SHRSP caused by long-standing hypertension.
This study confirmed again that high protein diet feeding decreased the incidence of stroke, and high fish protein diet did attenuate severe hypertension but high soybean protein diet did not affect the hypertension. Dietary amino acid analyses indicated that increases in total amino acids, essential amino acids and nonpolar amino acids but not acid or basic amino acids were significantly related to the reduction of stroke incidence. Among essential amino acids, lysine, threonine, isoleucine, and leucine contents were inversely related to stroke incidence, and methionine content was significantly related to the dietary antihypertensive effect of high protein diets. The prophylactic effect of high protein diets may be ascribed to some amino acid constituent.
The absorption of radioactive cholesterol tended to be increased, and the catabolism of cholesterol detected by the decay of radioactive cholesterol in the serum after the intraperitoneal injection was delayed in ALR in comparison with normotensive WK rats. The reactive hypercholesterolemia in the ALR which had been selectively bred for a greater hypercholesterolemia was ascribed to the decreased cholesterol catabolism.
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Plasma cholesterol was lower in spontaneously hypertensive rats (SHR), while plasma triglyceride and free fatty acid were increased in comparison with control normotensive Wistar-Kyoto (WK) rats. Correspondingly, [1-14C]-acetate incorporation into liver cholesterol was clearly decreased in SHR as compared with WK. As for lipogenic enzyme activities, glucose-6-phosphate dehydrogenase, malic enzyme and acetyl-CoA carboxylase in SHR were respectively decreased, increased and not significantly different, in comparison with WK rats. Liver cholesterol was rather low and cardiac triglyceride was slightly increased in SHR. Aortic cholesterol and triglyceride levels were not significantly different between SHR AND WK rats. Thus, SHR have an abnormality in lipid metabolism, especially in cholesterol synthesis, but the pathological implication of this in hypertension and related vascular lesions is not yet clear.
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