| Budget Amount *help |
¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1987: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1986: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Research Abstract |
The expressions of the renin, angiotensinogen and atrial natriuretic polypeptide (ANP) genes were studied in rats with varying sodium intakes and the spontaneously hypertensive rats (SHR). Messenger RNA (mRNA) for angiotensinogen and ANP was measured by a sensitive radiodensitometric cDNA hybridization assay. For the determination of renal renin mRNA, the 760-base pair Rsa I fragment containing the last exon of the rat renin gene was used as a probe for a radiodensitometric assay. In the high sodium state, plasma renin concentration (PRC), renal renin concentration (RRC) and renal renin mRNA decreased by 88% , 90% and 75% respectively. In the low sodium state,PRC,RRC,and renin mRNA increased 17-fold,2.5-fold and 4.5-fold respectively. With captopril treatment during sodium depletion, PRC and renin mRNA increased 144-fold and 17.1-fold respectively, and RRC increased 4.2-fold. The angiotensinogen mRNA level in the liver and kidney decreased in the high sodium state and increased in the low sodium state to similar extents. Captopril treatment decreased angiotensinogen mRNA in both organs by about half. Plasma ANP and ANP mRNA decreased in the low sodium state compared to the high sodium state, while atrial ANP content was unaltered in both low and high sodium states. These results demonstrate that sodium intake affects the expression of the renin, angiotensinogen and ANP genes. In both SHR and Wistar Kyoto rats (SHR) that were 4,8,12 and 16 weeks of age, PRA and PAC in SHR did not differ from these in WKY. Renal renin mRNA level and ANP mRNA level in the atrium did not change in both SHR and WKY. These data suggested that renal renin and atrial ANP may not contribute to increase the blood pressure.
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