[Carotid arterial stiffness parameter].
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Aging↗
Biomedical subjects
Fumihiro Tomoda
Publications and source records attributed to Fumihiro Tomoda.
Effects of uninephrectomy on renal structural properties in spontaneously hypertensive rats.
1. To investigate effects of a reduction in nephron numbers on renal structural properties in hypertension, either unilateral nephrectomy (UNX) or sham operation (SO) was performed at 5 weeks of age in spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats (n = 9 for each operation for each strain). 2. At 10-12 weeks of age, flow-pressure (F-P) and pressure-glomerular filtration rate (P-GFR) relationships were determined for maximally vasodilated, perfused kidneys. Kidneys were then perfusion fixed for histological analysis. 3. In the SO groups, the slope of F-P (minimal renal vascular resistance, reflecting overall luminal dimensions of pre- and post-glomerular vasculature) was greater in SHR than in WKY rats. The threshold pressure for beginning filtration at P-GFR (preglomerular to post-glomerular vascular resistance ratio) was higher in SHR than in WKY rats, but the slope of P-GFR (glomerular filtration capacity) did not differ between the two strains. These results suggest that vascular narrowing occurred, especially in the preglomerular resistance vessels in the kidneys of SHR, although glomerular filtration capacity was normal. 4. In UNX animals, the following results were obtained: (i) the slope of F-P was not affected in either strain; (ii) the pressure for beginning filtration at P-GFR was unchanged in WKY rats, but was decreased in SHR; (iii) the slope of P-GFR increased in WKY rats, but a compensatory adaptive increase was missing in SHR; and (iv) histologically, small increases in the luminal cross-sectional area of interlobular arteries and glomerular tuft area were observed in both strains. However, the increase in vascular lumen was more pronounced in SHR, whereas glomerular enlargement was greater in WKY rats. 5. These results suggested that UNX attenuates vascular narrowing of the preglomerular resistance vessels and glomerular structural adaptations to UNX (i.e. increased filtering capacity and glomerular enlargement) are impaired in SHR.
Animals↗
Angiotensin-converting enzyme-gene polymorphism is associated with collagen I synthesis and QT dispersion in essential hypertension.
AIM: This study tested the hypothesis that abnormal QT dispersion, an indicator of arrhythmogenic risk, is associated with angiotensin-converting enzyme (ACE) gene polymorphism and abnormalities of collagen metabolism. METHODS: A total of 132 patients with untreated essential hypertension (EHT) were recruited. QT dispersion corrected by heart rate (QTc) on a 12-lead electrocardiogram, ACE genotype, left ventricular mass index (LVMI) and E/A ratio using echocardiogram, plasma ACE activity and serum propeptide type I C-terminal procollagen (PICP) concentration, a marker of myocardial fibrosis, were determined. A normal control group (NC) of 200 normotensive subjects was used for comparison of QT dispersion. RESULTS: Number of EHT patients with ACE genotype I/I, I/D and D/D was 61, 52 and 19, respectively. LVMI and E/A ratio were similar in the three groups. Compared with subjects with I/I or I/D genotype, subjects with D/D showed higher plasma ACE activity (I/I: 13 +/- 0.6, I/D: 17 +/- 0.9, and D/D: 21 +/- 1.1 nmol/min per ml, mean +/- SE, P05) and serum PICP concentration (I/I: 106 +/- 5.4, I/D: 106 +/- 4.9, D/D: 140 +/- 12.1 ng/ml, P < 0.01). QTc dispersion was larger in the three hypertensive subgroups than in NC, and was the largest in EHT with D/D (NC: 0.037 +/- 0.001, I/I: 0.056 +/- 0.003, I/D: 0.055 +/- 0.002, D/D: 0.069 +/- 0.004 s, P < 0.05). CONCLUSION: ACE D/D genotype could be associated with an elevation of serum PICP concentration possibly leading to myocardial fibrosis and increased QT dispersion.
Adult↗
Relation of circulating blood volume to left ventricular geometry in essential hypertension.
To investigate whether circulating blood volume contributes to left ventricular (LV) geometry, 60 outpatients with untreated, mild to moderate essential hypertension and 45 normotensives were studied. Based on echocardiographic LV mass index and relative wall thickness, four patterns of LV geometry, i.e., normal left ventricle, concentric remodeling, eccentric hypertrophy and concentric hypertrophy, were identified. Plasma volume and blood volume were measured by the 131I labeled human serum albumin technique. LV end-diastolic volume was greater in patients with eccentric hypertrophy than in the groups of patients with normal left ventricles, concentric remodeling, or concentric hypertrophy or in normotensive subjects. No differences were found in systolic function among the five groups. Both plasma volume and blood volume were decreased in the concentric remodeling group as compared with the other four groups. However, there were no differences in plasma volume or blood volume among the normal left ventricle, eccentric hypertrophy and concentric hypertrophy groups. These data indicate that a small LV chamber in cases of "concentric remodeling" may be related to decreased plasma and blood volumes, but an enlarged LV chamber in cases of "eccentric hypertrophy" is not likely to be related to either plasma or blood volume levels in mild to moderate untreated essential hypertension.
Adult↗