Plasma and tissue levels of proangiotensin-12 and components of the renin-angiotensin system (RAS) following low- or high-salt feeding in rats.
The renin-angiotensin system (RAS) is an essential regulator of the blood pressure and body fluid balance, but the processing cascade or role of the tissue RAS remains obscure. Proangiotensin-12 (proang-12), a novel angiotensin peptide recently discovered in rat tissues, is assumed to function as a factor of the tissue RAS. To investigate the tissue production of proang-12, we measured the circulating and tissue components of the RAS including proang-12 following low-, normal-, or high-salt feeding in rats. Twelve-week-old male Wistar rats were fed a low-salt 0.3% NaCl or high-salt 8% NaCl diet for 7 days and compared with those fed a normal-salt diet of 0.7% NaCl. Low-salt feeding elevated the plasma renin activity and aldosterone concentration, resulting in significant increases in Ang I and Ang II levels in the plasma or kidney tissue, as compared with the normal- or high-salt group. Despite the increases in plasma renin activity, Ang I, and Ang II, the proang-12 levels in plasma and various tissues including the kidneys, small intestine, cardiac ventricles, and brain remained unchanged following low-salt feeding. These results suggest that peptide levels of proang-12 in rat plasma and tissues are regulated in a manner independent of the circulating RAS.
Nagata
Sayaka
S
Circulatory and Body Fluid Regulation, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki 889-1692, Japan. saya223@fc.miyazaki-u.ac.jp
Kato
Johji
J
Kuwasako
Kenji
K
Kitamura
Kazuo
K
D000450:Aldosterone / Q000097:blood / Q000378:metabolism; D000803:Angiotensin I / Q000097:blood / Q000378:metabolism; D000804:Angiotensin II / Q000097:blood / Q000378:metabolism; D000808:Angiotensinogen / Q000097:blood* / Q000378:metabolism*; D000818:Animals; D008297:Male; D011863:Radioimmunoassay; D051381:Rats; D017208:Rats, Wistar; D012083:Renin / Q000097:blood / Q000378:metabolism; D012084:Renin-Angiotensin System / Q000187:drug effects* / Q000502:physiology*; D012965:Sodium Chloride / Q000494:pharmacology*
D000808:Angiotensinogen; D000804:Angiotensin II; D012965:Sodium Chloride; D000450:Aldosterone; D000803:Angiotensin I; D012083:Renin