Molecular Biology of Renin and Regulation of Its Gene

Publisher Summary Active renin in the plasma comes almost entirely from the kidneys. Total nephrectomy of both humans and animals causes plasma renin levels to disappear. In addition to active renin secreted from juxtaglomerular (JG) cells, prorenin is also present in the plasma at levels 5–10 times that of active renin. After nephrectomy, circulating prorenin declines but does not disappear, suggesting that it is secreted from sites outside of the kidneys. Indeed, expression of the renin gene has been detected in a number of extrarenal tissues, including the adrenal and pituitary glands, the eye, and reproductive tissues, and it is therefore likely that these tissues contribute to prorenin found in the circulation. Because only the JG cells of the kidneys produce active renin, it is not surprising that the mechanisms that regulate normal renin secretion and renin gene expression reside primarily in the kidneys. Defects in the physiological control of renin release may also play an important part in the contribution of the renin–angiotensin–aldosterone system to disease. Although only about 10% of all hypertensive patients have elevated plasma renin levels, even a normal plasma renin level in a hypertensive patient is inappropriate because the high blood pressure suppresses renin secretion.