Endogenous sodium pump inhibitors and age-associated increases in salt sensitivity of blood pressure in normotensives.
Factors that mediate increases in salt sensitivity of blood pressure with age remain to be clarified. The present study investigated 1) the effects of high-NaCl intake on two Na pump inhibitors, endogenous ouabain (EO) and marinobufagenin (MBG), in middle-aged and older normotensive Caucasian women; and 2) whether individual differences in EO and MBG are linked to variations in sodium excretion or salt sensitivity. A change from 6 days of a lower (0.7 mmol.kg(-1).day(-1))- to 6 days of a higher (4 mmol.kg(-1).day(-1))-NaCl diet elicited a sustained increase in MBG excretion that directly correlated with an increase in the fractional Na excretion and was inversely related to age and to an age-dependent increase in salt sensitivity. In contrast, EO excretion increased only transiently in response to NaCl loading and did not vary with age or correlate with fractional Na excretion or salt sensitivity. A positive correlation of both plasma and urine levels of EO and MBG during salt loading may indicate a casual link between two Na pump inhibitors in response to NaCl loading, as observed in animal models. A linear mixed-effects model demonstrated that age, dietary NaCl, renal MBG excretion, and body mass index were each independently associated with systolic blood pressure. Thus, a sustained increase in MBG in response to acutely elevated dietary NaCl is inversely linked to salt sensitivity in normotensive middle-aged and older women, and a relative failure of MBG elaboration by these older persons may be involved in the increased salt sensitivity with advancing age.
Anderson
David E
DE
Laboratory on Cardiovascular Science, National Institute on Aging, Intramural Research Program, Gerontology Research Center, Baltimore, MD 21224-6825, USA.
Fedorova
Olga V
OV
Morrell
Christopher H
CH
Longo
Dan L
DL
Kashkin
Vladimir A
VA
Metzler
Jessica D
JD
Bagrov
Alexei Y
AY
Lakatta
Edward G
EG
D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging / Q000378:metabolism*; D001794:Blood Pressure; D015992:Body Mass Index; D002018:Bufanolides / Q000097:blood / Q000378:metabolism* / Q000652:urine; D004791:Enzyme Inhibitors / Q000097:blood / Q000378:metabolism* / Q000652:urine; D005260:Female; D006801:Humans; D006973:Hypertension / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology; D016014:Linear Models; D008875:Middle Aged; D008954:Models, Biological; D009318:Natriuresis; D010042:Ouabain / Q000097:blood / Q000378:metabolism* / Q000652:urine; D017673:Sodium Chloride, Dietary / Q000008:administration & dosage / Q000009:adverse effects / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013599:Systole; D013997:Time Factors; D015854:Up-Regulation
D002018:Bufanolides; D004791:Enzyme Inhibitors; D017673:Sodium Chloride, Dietary; C093896:marinobufagenin; D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase