Rhythm characteristics of plasma renin, aldosterone and cortisol in five subtypes of mesor-hypertension.

The possible role of the renin-angiotensin system and ACTH in controlling the temporal organization of circadian rhythm of aldosterone was studied in patients with mesor-hypertension (MH) by simultaneous radioimmunological determinations of within-day changes in plasma renin, aldosterone and cortisol. Thirty-nine uncomplicated, untreated mesor-hypertensive patients, divided in subtypes, were examined. The interrelationship between the rhythm components revealed that the circadian cyclicity of aldosterone in both mesor-normotensive and mesor-hypertensive subjects, with either normal or high renin patterns, has a similar timing in acrophase with renin periodicity, which leads the circadian cortisol rhythm. In low-renin mesorhypertensive subjects a circadian rhythm of aldosterone and cortisol, but not of renin, remains demonstrable. The confidence limits of the estimated acrophase for circadian cortisol rhythm do not, however, overlap the confidence arcs of the aldosterone phase. These findings suggest that in normal or high renin MH subjects the aldosterone rhythmicity is mainly controlled by the renin-angiotensin system. Conversely in low-renin MH subjects the temporal organization of the aldosterone circadian sequences seems to be completely independent of renin-angiotensin control.