Hypertension, Na+/Ca2+ exchanger, and Na+, K+-ATPase.
Hypertension is the most prevalent risk factor for stroke, myocardial infarction, or end-stage renal failure. The critical importance of excess salt intake in the pathogenesis of hypertension is widely recognized, but the mechanisms whereby salt intake elevates blood pressure have puzzled researchers. Recent studies using Na+/Ca2+ exchange inhibitors and genetically engineered mice provide evidence that vascular Na+/Ca2+ exchanger type 1 (NCX1) is involved in the development of salt-dependent hypertension. Endogenous cardiac glycosides, which may contribute to salt-dependent hypertension, seem to be necessary for NCX1-mediated hypertension. Intriguingly, studies using knock-in mice with modified cardiac glycoside binding affinity of Na+,K+-ATPases provide a clear demonstration that this cardiac glycoside-binding site plays an important role in blood pressure regulation. Taken all together: (1) endogenous cardiac glycosides are secreted after high salt intake; (2) these cardiac glycosides inhibit Na+,K+-ATPase in vascular smooth muscle cells; (3) this inhibition results in the elevation of local Na+ on the submembrane area; and (4) this elevation of local Na+ facilitates Ca2+ entry through NCX1, resulting in vasoconstriction. This proposed pathway may have enabled us to explain how to link dietary salt to hypertension.
Iwamoto
T
T
Department of Pharmacology, School of Medicine, Fukuoka University, Fukuoka, Japan. tiwamoto@cis.fukuoka-u.ac.jp
Kita
S
S
D000732:Androstanols / Q000627:therapeutic use; D000814:Aniline Compounds / Q000627:therapeutic use; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D002118:Calcium / Q000378:metabolism / Q000502:physiology; D002301:Cardiac Glycosides / Q000097:blood / Q000378:metabolism; D002319:Cardiovascular System / Q000503:physiopathology; D002462:Cell Membrane / Q000737:chemistry / Q000502:physiology; D006801:Humans; D006973:Hypertension / Q000188:drug therapy / Q000209:etiology* / Q000503:physiopathology*; D007668:Kidney / Q000503:physiopathology; D009131:Muscle, Smooth, Vascular / Q000201:enzymology; D010042:Ouabain / Q000037:antagonists & inhibitors; D010647:Phenyl Ethers / Q000627:therapeutic use; D011485:Protein Binding; D012964:Sodium / Q000032:analysis / Q000097:blood / Q000502:physiology; D012982:Sodium, Dietary / Q000009:adverse effects*; D019831:Sodium-Calcium Exchanger / Q000037:antagonists & inhibitors / Q000502:physiology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000032:analysis / Q000502:physiology*; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology
D000732:Androstanols; D000814:Aniline Compounds; D002301:Cardiac Glycosides; D010647:Phenyl Ethers; C430918:SEA 0400; D012982:Sodium, Dietary; D019831:Sodium-Calcium Exchanger; D010042:Ouabain; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; C106263:rostafuroxin; D002118:Calcium