Salt sensitivity and systemic hypertension in the elderly.
Aging in industrialized societies is accompanied by increases in the incidence and prevalence of hypertension, with a disproportionately greater increase occurring among aging blacks than among aging whites. This geriatric hypertension is generally of a salt-sensitive nature with a disproportionate frequency of isolated systolic hypertension. Although salt-taste acuity declines with age, salt sensitivity among the elderly does not appear to result from a compensatory increase in salt intake. Rather, age-related increases in salt sensitivity result, in part, from a reduced ability to appropriately excrete a salt load, which is due to a decline in renal function and to a reduced generation of natriuretic substances such as prostaglandin E2 and dopamine. Age-associated declines in the activity of membrane sodium/potassium-adenosine triphosphatase (Na/K-ATPase) may also contribute to geriatric hypertension because this results in increased intracellular sodium that may cause reduced sodium-calcium exchange and thereby increase intracellular calcium and vascular resistance. Reductions in cellular calcium efflux due to reduced calcium-ATPase activity may similarly cause an increase in intracellular calcium and vascular resistance. Increasing dietary calcium intake may represent an effective nonpharmacologic treatment for some salt-sensitive persons because it appears to reduce intracellular calcium by (1) suppressing parathyroid hormone-mediated calcium influx, (2) increasing Na/K-ATPase activity, and (3) reducing intravascular volume due to calcium-induced natriuresis.
Zemel
M B
MB
Division of Endocrinology and Hypertension, Wayne State University, Detroit, Michigan 48202.
Sowers
J R
JR
D000368:Aged; D000375:Aging / Q000502:physiology; D044383:Black People; D001794:Blood Pressure; D002118:Calcium / Q000378:metabolism; D004342:Drug Hypersensitivity / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology*; D008297:Male; D009747:Nutritional Physiological Phenomena; D012982:Sodium, Dietary / Q000009:adverse effects* / Q000378:metabolism; D044465:White People
D012982:Sodium, Dietary; D002118:Calcium