Hormones and blood pressure: clues from chronobiology.

Results relating to the study of several hormones homeostatically related to blood pressure (renin-angiotensins, mineralocorticoids, glucocorticoids, atrial natriuretic factor) are reviewed. Most experimental data and clinical observations concerning 'hypertension' are specified neither as to circadian stage nor do they assess rhythm parameters. Such homeostatic data suggest that several groupings of hormones play a major role in coordinating blood pressure. The majority of hormones involved have multiple actions and the diversity of effects is often unexplained in homeostatic terms. In chronobiology, opposite effects are seen in response to the same stimulus depending upon the stage of the organism's multifrequency rhythms and their intermodulation. The periodic pattern exhibited by some of the hormones coordinating blood pressure in health and the capability of these hormones to modify temporal structure, either inducing a change in timing (circadian blood pressure ecphasia) or in amplitude (amplitude-hypertension) or in mean level of the values (MESOR-hypertension) are reviewed as well.