Renin substrate in rat mesenteric artery.

The concentration of renin substrate (RS) was measured in rat mesenteric artery tissue. The concentration of this substrate both in arterial tissue and in plasma was markedly higher in rats 1 day after bilateral nephrectomy than in sham-operated controls, the percentage difference being higher in plasma than in arterial RS. Conversely, the decrease apparently induced 3 days after adrenalectomy (i.e., the difference in RS concentration from sham-operated rats) was greater in arterial tissue than in plasma. This finding may be explained by changes in RS concentrations induced by the sham operation. Sham surgery itself increased plasma RS after 1 day (but not after 3 days) and arterial RS after 3 days (but not after 1 day). There was a positive correlation between arterial and plasma renin substrate concentration for the overall results but not within individual groups. As renin and angiotensin-converting enzyme activity are also present in arterial tissues, all the necessary components for local generation of angiotensin II have now been shown to be present within the wall of resistance vessels.