Salt, Hypertension, and Cardiovascular Diseases

The relationship between salt and hypertension is well established, and salt restriction is widely recommended in the management of hypertension. However, people living in northeast Asia have consumed large amount of salt, and the prevalence of hypertension and the incidence of stroke have been high in that area. Mechanisms of salt-induced hypertension may be complex, but volume expansion in the presence of impaired natriuretic capacity of the kidney and action on the central nervous system and neurohormoral pathways seem to be important. Salt is also involved in changes in blood pressure (BP) caused by other factors, such as weight gain, stress, exercise, potassium, catecholamines, angiotensin, and aldosterone. The interaction between sodium and aldosterone appears to play a critical role in the development of organ damage. The depressor effect of salt restriction in hypertensive patients is well demonstrated although the response of BP varies widely among individuals. Salt restriction decreases BP throughout 24 hours, and its effect may be greater during night compared to daytime in salt-sensitive nondippers. Although excess salt consumption can cause cardiovascular diseases through its effect on BP, recent studied have shown that the association of salt consumption and cardiovascular diseases, such as stroke and heart failure, is independent of BP. Salt reduction is important in the prevention of cardiovascular diseases, however, the effect and safety of aggressive salt restriction remain to be clarified. It is difficult to accomplish and maintain the salt reduction. Both population strategy and individualized approach are important to reduce salt consumption.

Bio-Molecular Markers for Cardiovascular Disease: Significance of Natriuretic Peptides and Adrenomedullin

There are many established and proposed bio-molecular markers for cardiovascular disease, including vasoactive substances, substances related to inflammation and oxidative stress, and substances involved in tissue structure and remodeling. Among these substances, we focused on natriuretic peptides and adrenomedullin (AM) as clinically useful bio-molecular markers in this review. Three natriuretic peptides-atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and C-type natriuretic peptide (CNP)-play various important roles in the cardiovascular system. ANP and BNP are released from the heart and exist primarily as circulating hormones. They participate in the regulation of blood pressure and fluid levels. Plasma levels of ANP and BNP are increased in various pathological conditions such as heart failure, myocardial infarction, and hypertension with cardiac hypertrophy. BNP is now essential as a biochemical marker in managing patients with cardiovascular disease. CNP is mainly produced in vascular endothelium. It contributes to smooth muscle relaxation and growth inhibition as a local hormone, but it is also synthesized in cardiac fibroblasts and inhibits fibroblast proliferation and myocyte growth. However, the significance of plasma CNP levels remains to be elucidated. AM is widely distributed in various organs and tissues, including the cardiovascular system. Not only it is a potent vasodilator peptide, but it also has protective effects against vascular and cardiac cell injury and excessive growth. Plasma AM levels are increased in several cardiovascular diseases, including hypertension, heart failure, myocardial infarction, and atherosclerotic disease, and AM appears to be a predictive and prognostic marker in the setting of cardiovascular disease.