Hypertension Caused by Disruption of the Circadian System: Blood Pressure Regulation at Multiple Levels

The chapter begins with explaining the effects of deleting of Cry genes which causes complete loss of circadian rhythms and leads to hyperaldosteronism and salt‐sensitive hypertension. Aldosterone induces reabsorption of ions and water in the kidneys, thereby increasing blood volume, leading to higher blood pressure. Since primary aldosteronism (PA) carries a higher risk of developing cardiovascular complications, accurate diagnosis and treatment of idiopathic hyperaldosteronism are particularly important. The pathological conditions of Cry‐null mice may play an important role in unraveling the pathophysiology of PA and salt‐sensitive hypertension in humans. Intriguingly, Miyajima et al. (1991) reports that muscle sympathetic nerve activity increases in essential hypertension and renovascular hypertension but decreases in PA. Baroreflex is very important for rapid regulation of blood pressure. The regulation of blood pressure is crucially important and, thus, is controlled by multilayered regulatory systems.