| Budget Amount *help |
¥3,240,000 (Direct Cost: ¥3,000,000、Indirect Cost: ¥240,000)
Fiscal Year 2007: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2006: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2005: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Research Abstract |
Recently, it has been recognized that even mild renal dysfunction is a strong predictor for future cardiovascular diseases and the risks of cardiovascular diseases are enhanced as renal function deteriorates. Therefore, World Kidney Day, or global health awareness campaign focusing on the importance of kidneys and reducing the frequency and impact of chronic kidney disenre (CKD) and its associated health problems worldwide, started in March, 2006. We previously found that there was an inverse relationship between glomerular filtration rate and the night/day ratio of blood pressure (BP) in patients with CKD (Kidney International. 2004 Feb ; 65 (2) : 621-625), and have postulated the "renal mechanism of non-dipper" that reduced renal capacity to excrete sodium into urine causes nocturnal elevation of BP, i.e., non-dipper, to compensate for diminished daytime natriuresis by enhancing pressure natriuresis during sleep. To support the proposal, we proved that the patients with severer renal
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dysfunction showed non-dipper circadian rhythm of natriuresis and required a longer duration during sleep until BP began to fall. We defined the duration as dipping time (Hypertension. 2008 Dec ; 52 (6) : 1155-1160). Here, the patients with diminished preserve capacity to excrete sodium into urine during the day are expected to demonstrate the attenuation of natriuresis on shifting the body position from supine to upright because one may keep upright position for a longer time during the day rather than during the night. Therefore, in this study we investigated whether postural change in natriuresis can detect the circadian rhythm of BP, as well as that of natriuresis, or not. In other words, we focused on postural change in natriuresis to investigate whether we can portray daytime as an upright position, and night-time as a supine position to diagnose the patients' circadian BP rhythm as dipper or as non-dipper type. As a result, the upright/supine ratio of natriuresis showed negative correlation with the night/day ratios of BP (r=-0.48, p=0.03) and natriuresis (r=-0.49, p=0.02) suggesting that postural change from supine to upright position decrease urinary sodium excretion rate more markedly especially in patients with non-dipper circadian rhythms of BP and natriuresis. We think of the impaired renal preserve to excrete urinary sodium as the essential component of both non-dipper pattern of BP rhythm and sodium sensitivity of BP. Both of them are considered to be risk factors for cardiovascular disease. Therefore, our present study indicated, the potential that we can detect the patients' circadian BP rhythm, dipper or non-dipper, by testing their postural change in natriuresis, possibly leading to detect their sodium sensitivity of BP and to estimate their risk for cardiovascular diseases. Less
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