Pathophysiology of salt sensitivity hypertension.
Dietary salt intake is the most important factor contributing to hypertension, but the salt susceptibility of blood pressure (BP) is different in individual subjects. Although the pathogenesis of salt-sensitive hypertension is heterogeneous, it is mainly attributable to an impaired renal capacity to excrete sodium (Na(+) ). We recently identified two novel mechanisms that impair renal Na(+) -excreting function and result in an increase in BP. First, mineralocorticoid receptor (MR) activation in the kidney, which facilitates distal Na(+) reabsorption through epithelial Na(+) channel activation, causes salt-sensitive hypertension. This mechanism exists not only in models of high-aldosterone hypertension as seen in conditions of obesity or metabolic syndrome, but also in normal- or low-aldosterone type of salt-sensitive hypertension. In the latter, Rac1 activation by salt excess causes MR stimulation. Second, renospecific sympathoactivation may cause an increase in BP under conditions of salt excess. Renal beta2 adrenoceptor stimulation in the kidney leads to decreased transcription of the gene encoding WNK4, a negative regulator of Na(+) reabsorption through Na(+) -Cl (-) cotransporter in the distal convoluted tubules, resulting in salt-dependent hypertension. Abnormalities identified in these two pathways of Na(+) reabsorption in the distal nephron may present therapeutic targets for the treatment of salt-sensitive hypertension.
Department of Nephrology and Endocrinology, University of Tokyo Graduate School of Medicine, Tokyo, Japan.
Katsuyuki
K
Ando
Toshiro
T
Fujita
D000450:Aldosterone / Q000378:metabolism; D001794:Blood Pressure; D006801:Humans; D006973:Hypertension / Q000139:chemically induced* / Q000378:metabolism*; D007668:Kidney / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D018161:Receptors, Mineralocorticoid / Q000378:metabolism; D015398:Signal Transduction; D012964:Sodium / Q000378:metabolism* / Q000652:urine; D017673:Sodium Chloride, Dietary / Q000009:adverse effects* / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000378:metabolism
D018161:Receptors, Mineralocorticoid; D017673:Sodium Chloride, Dietary; D000450:Aldosterone; D012964:Sodium; D017346:Protein Serine-Threonine Kinases; C433806:WNK4 protein, human; D020830:rac1 GTP-Binding Protein