Plasma Renin Activity and Angiotensin Pressor Dose in Hypertension: Correlation and Diagnostic Implications

Abstract

IntoductionExtensive experimental and clinical studies during recent years have shown the importance of the renin-angiotensinaldosterone system in the regulation of sodium and water balance. There is, however, still some controversy about the significance of these substances in the pathogenesis of hypertension. The fact that markedly raised secretion of renin, angiotensin, and aldosterone may be associated with normal or even reduced blood pressure has been a perpetual source of doubt in this connexion (Gross et al., 1964 ;Brown et al., 1967).The elaboration of methods of assessing these three substances has facilitated the diagnosis of certain forms of hypertension. The combination of high blood pressure, low renin, and elevated aldosterone suggests Conn's syndrome Brown et al., 1965;Weidmann et al., 1967b). Stimulation of the renin-releasing mechanisms seems to be more effective in patients with renovascular hypertension than in those with essential hypertension (Weidmann et al., 1967a) (Breckenridge, 1965 ;Fitz et al., 1965)

Studies with Pinealectomized Rats

“…In man, exogenous angiotensin II increases the blood pressure the less the higher the plasma renin activity [17], Our present results with rats are in agreement with this finding. The mechanism by which Studies with Pinealectomized Rats 83 the hypertension was induced may have played a role in these varying results.…”

Effects of sodium salts on pressor reactivity in salt-sensitive men.

“…- 32 In our present study, both sodium salts lowered plasma angiotensin II levels and renin activity while enhancing pressor response to angiotensin II in both groups. During both high sodium regimens, however, pressor response was higher and plasma levels of angiotensin II and renin activity tended to be lower in the salt-sensitive than in the salt-resistant subjects.…”

Recent pathogenic aspects in essential hypertension and hypertension associated with diabetes mellitus

“…As mentioned already, in normal man inverse relationships between pressor factors such as plasma NE or renin levels and pressor responsiveness to NE or angiotensin II, respectively, appear to maintain a physiologic equilibrium [102,139,179,194], possibly as yet another feeedback mechanism in support of blood pressure homeostasis. Consequently, pharmacologic inhibitors of a pressor factor should be capable of lowering blood pressure by this mechanism only if the suppression of the pressor factor is not accompanied by an equivalent increase in pressor reactivity.…”

“…Considering the physiologic inverse relationship between circulating renin and cardiovascular pressor responsiveness to angiotensin II [35], no clearcut abnormality could be demonstrated in patients with established essential hypertension [139,179]. However, preliminary observations in our laboratory suggested that in patients with borderline hypertension [124] or younger hypertensive patients below the age of 45 years [126] pressor responsiveness to angiotensin at a given endogenous plasma renin may be significantly increased; this discrepancy was not apparent in middle-aged and older patients (> 45 yr) with essential hypertension.…”