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Biomedical subjects

R Horie

Publications and source records attributed to R Horie.

At least 73 records · Page 4Linked to original sources
PubMed1985

Biochemical aspects of salt-induced, pressure-independent left ventricular hypertrophy in rats.

In an attempt to investigate the effect of chronic salt loading on heart size and biochemical composition, sixty 3-month-old male Wistar-Kyoto rats (WKY) were equally divided into two groups: One group was given 1% NaCl in drinking water, and the other group was given tap water as the control. After 7 months, five randomly selected rats from each group were examined for body weight (BW), indirect blood pressure (BP), hematocrit (Hct), and organ weights. Ventricles of the heart, aorta, and mesenteric arteries were biochemically analyzed for collagen (C) and noncollagenous protein NC) and deoxyribonucleic acid (DNA). Although here was no difference between the salt and control groups in BP (129 +/- 3 mmHg vs. 125 +/- 4 mmHg, mean +/- SE), BW (376 +/- 8 g vs. 372 +/- 5 g) and Hct (42.8% +/- 1.0% vs. 44.3% +/- 0.8%), left ventricular weight (857 +/- 19 mg vs. 788 +/- 8 mg) and kidney weight (2.59 +/- 00.9 g vs 2.31 +/- 0.05 g) were both significantly (P less than 0.01) greater in the salt group, whereas the weights of the right ventricle, aorta, and adrenal glands were equal. Biochemical analysis showed significant increase in NC/DNA ratio and total collagen content as well as decreased DNA concentration in the left ventricle of the salt group compared with the control, suggesting hypertrophy rather than hyperplasia of myocardial cells with concomitant activation of collagen synthesis. Since the manner of reactive collagen production appeared different from that reported for spontaneously hypertrophic rats (SHR) or in hypoxia- or aortic constriction-induced cardiac hypertrophy, some unique mechanism may be involved in salt-induced cardiac hypertrophy.

Adrenal Glands↗
PubMed1985

Electronmicroscopic autoradiographic study of the distribution of 3H-diltiazem in myocardial cells.

The distribution of 3H-diltiazem in myocardial cell organelles was studied using an electronmicroscopic autoradiographic technique. At 3, 5 and 10 min after 3H-diltiazem injection, silver grains, which indicate the existence of diltiazem, were detected in plasma membranes and intracellular organelles. Silver grains in T systems were observed more frequently at 3 min than at 5 and 10 min. In contrast, silver grains in sarcoplasmic reticula and mitochondria apparently increased with the passage of time. These findings suggest that diltiazem is transported through the T system and may accumulate within the sarcoplasmic reticula and mitochondria. Furthermore, our study revealed morphologically for the first time that the intracellular sites of action where diltiazem was directed were possibly the mitochondria.

Animals↗
PubMed1985

Sympathetic factors in the cardiovascular complications of hypertension: evidence in genetic models for hypertension, stroke and atherosclerosis.

The role of the nervous system in the pathogenesis of cardiovascular complications in hypertension has been clarified to a great extent in genetic rat models for hypertension, stroke and atherosclerosis, especially in the evolution of cardiovascular hypertrophy in hypertension, the most common process related to the pathogenesis and complications of hypertension, in the development of stroke, one of the most common sequelae of hypertension itself and in the pathogenesis of atherosclerotic vascular diseases, the most usual cause of myocardial infarction.

Animals↗
PubMed1984

Simple method for sampling consecutive 24-hour urine for epidemiological and clinical studies.

'Aliquot cups' a newly devised tool for collecting 24-hour urine samples were useful and accurate enough for the estimation of individual 24-hour excretion of sodium and potassium. Data from 24-hour collections for 31 days for 5 healthy volunteers showed relatively large intra- and inter-individual variation. These data suggest that at least 5 consecutive days of urine collection would be needed to make a reasonable estimate of daily intake.

Adult↗
PubMed1984

Dietary prevention of hypertension in animal models and its applicability to human.

Experimental studies in animals and epidemiological studies have suggested that the interaction between genetic and environmental factors is important in hypertension associated with excess salt intake and other dietary factors such as K, protein and fatty acid intake greatly modify the effect of salt on blood pressure in individuals with low or high salt sensitivity. Thus, the detection of salt sensitivity and the modification of salt intake as well as other dietary factors are expected to contribute to the primary prevention of cardiovascular diseases associated with hypertension.

Animals↗
PubMed1984

Common cellular disposition to hypertension and atherosclerosis.

The genetically hypertensive rat models, spontaneously hypertensive rats (SHR) and especially stroke-prone SHR (SHRSP), both develop arterial fat deposits quickly when fed high cholesterol diets. Therefore the morphological and functional characteristics of cultured vascular smooth muscle cells (SMC) from the aorta of SHR, SHRSP and normotensive Wistar-Kyoto (WKY) rats have been compared in order to demonstrate the common cellular mechanisms which induce hypertension and atherosclerosis. Cultured SMC became differentiated after short-term foetal calf serum exclusion from the medium, and despite the general concept of their noncontractility there was opticometric evidence that subcultured SMC contract spontaneously. Smooth muscle cells from SHR, but especially from SHRSP, showed enhanced proliferation which was inhibited by a Ca-antagonist, and accelerated lipid incorporation. It is concluded that these SMC are primarily predisposed to hypertension as well as to atherosclerosis.

Animals↗
PubMed1982

Effect of unilateral carotid ligation on brainstem PNMT activity.

Phenylethanolamine N-methyltransferase (PNMT) activity in the C1 and C2 regions of the brainstem was assayed in normotensive Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) with or without unilateral carotid artery ligation. PNMT activity was significantly higher in SHR than in WKY (P less than 0.01). PNMT activity in the C1 and C2 regions on non-ligated side in both WKY and SHR was significantly elevated compared with that on the ligated side. These results indicate that the activity of PNMT in adrenergic neurons may respond to baroreflex activation and that adrenergic neurons may be involved in blood pressure regulation.

Animals↗
PubMed1982

Symptomatological classification in the development of stroke in stroke-prone spontaneously hypertensive rats.

The developmental course of cerebrovascular diseases was examined by comparative neurological and pathological studies in stroke-prone SHR (SHRSP) which died spontaneously or were sacrificed. Behavioral status during their life span could be simply divided into 4 patterns, i.e., "no abnormalities", "irritable", "lethergic" and "akinetic" named Grades 0, I, II and III, respectively (Yamori's Classification). Grades I, II and III of behavioral status corresponded well to symptomato-pathoanatomically divided 3 stages (relating to brain edema), i.e., Stages I, II and III, respectively.

Animals↗
PubMed1982

Dietary risk factors of stroke and hypertension in Japan -- Part 1: Methodological assessment of urinalysis for dietary salt and protein intakes.

In our attempt to design a method which would be more reliable than dietary survey interviews when estimating salt and protein intakes in a population survey, a urinalysis-related study was done on volunteers. Urinary sodium (Na), urea nitrogen (UN) and inorganic sulfate (SO4), all indices of dietary salt, protein and sulfoamino acids, respectively, were confirmed to reflect the nutritional condition. Interaction between salt and protein was not observed at least at the dietary levels used in the present study (for salt, 0.33 and 0.1 g/kg body weight/day; for protein, 1.6 and 0.7 g/kg body weight/day). Excretion of components was delayed several days or more after dietary ingestion, and nutritional estimation by urinalysis, therefore, may not be so much affected by daily variables in the diet intake. Further, partial urine samples proved to have a highly significant correlation with 24-hour (hr) urine, as for urinary Na, potassium (K), SO4, UN and their creatinine (Cr) ratios, thus indicating the availability of partial urine samples as substitutes for 24-hr urine specimens. Thus, urinalysis is a more readily facilitated, more scientific and more quantitative method for epidemiological nutritional surveys.

Adult↗
PubMed1982

Dietary risk factors of stroke and hypertension in Japan -- Part 2: Validity of urinalysis for dietary salt and protein intakes under a field condition.

Utility of urinalysis as a method for estimating dietary salt and protein intakes was examined in volunteers from farming and fishing villages in Japan and the data was compared to findings in a survey on diets. We found that partial urine samples and even a fasting single spot urine in the a.m. could serve as valid substitutes for 24-hour (hr) urine collections. Further, significant correlations were obtained between levels of salt in the diet estimated by survey interviews and urinary sodium (Na) and between interview-estimated dietary total or animal protein and urinary inorganic sulfate (SO4). In comparative studies between farming and fishing villages, almost the same findings, higher salt in a farming village and higher animal protein in a fishing village, were obtained in the urinalysis and the survey on diets. These findings clearly indicate that urinalysis, as a method for estimating dietary salt and protein intake in population surveys, has distinct advantages.

Adult↗
PubMed1982

Dietary risk factors of stroke and hypertension in Japan -- Part 3: Comparative study on risk factors between farming and fishing villages in japan.

General medical examinations were performed in two rural areas of Shimane Prefecture in Japan, one was a farming village and the other a fishing village where incidences of death due to stroke differed, higher in the former and lower in the latter. Comparisons were made on salt and protein intake by analyzing the fasting single spot urine collected in the morning and by blood tests. Urine samples were analyzed for sodium (Na), potassium (K), urea nitrogen (UN), inorganic sulfate (SO4) and creatinine (Cr) and blood samples for cholesterol (Chl), triglyceride (TG), hematocrit (Ht) and hemoglobin (Hb). Blood pressure, Na/Cr, Na/K and Ht were higher in the farming village and K/Cr, UN/Cr, SO4/Cr, SO4/UN, Chl and TG were higher in the fishing village. These findings indicate the higher salt intake and lower intake of K, animal protein and fat in the farming village. This typical dietary pattern of the Japanese may explain the higher incidence of hypertension and stroke in the farming village.

Adult↗
PubMed1981

Mechanisms of structural vascular changes in genetic hypertension: analyses on cultured vascular smooth muscle cells from spontaneously hypertensive rats.

1. The basic mechanism underlying the structural vascular changes occurring in hypertension was studied in cultured aortic smooth muscle cells (SMC) obtained by an explant method from spontaneously hypertensive rats (SHR) and stroke-prone SHR (SHRSP) and compared with that in normotensive Wistar--Kyoto (WKY) rats. 2. The growth rate of SMC from SHR and SHRSP at the age of 2.5--11 months was greater than that of SMC from WKY rats even after repeated passages. 3. [3H]Thymidine and [14C]leucine incorporation, and ornithine decarboxylase (ODC) activity of SMC were increased in SHR and SHRSP in comparison with WKY rats. 4. The application of isoprenaline but not noradrenaline to the culture media increased ODC activity acutely in SMC from WKY rats and this increase was blocked by propranolol. 5. These results indicate that SMC from SHR and SHRSP are more prone to proliferate than those from WKY rats and that a beta-adrenergic neurohumoral mechanism accelerates SMC growth independently of blood pressure.

Animals↗