Salt, endogenous ouabain and blood pressure interactions in the general population.
OBJECTIVE
Experimental data show that ouabain is a modulator of the sodium-potassium pump, which plays an important role in sodium homeostasis and blood pressure regulation. We investigated the distribution of plasma ouabain in the general population in relation to blood pressure and other determinants of sodium homeostasis.


METHODS
In 379 subjects enrolled in a Belgian population study, we measured plasma ouabain, clinical characteristics including blood pressure, serum and urinary electrolytes, urinary aldosterone excretion, various lifestyle factors, and the Gly460Trp polymorphism of the alpha-adducin gene. Our statistical methods included analysis of covariance and multiple linear regression.


RESULTS
Plasma ouabain (median, 140 pmol/l) correlated independently and positively with male gender (n = 182, P = 0.002), smoking (n = 116, P = 0.05), urinary potassium excretion (mean 69 mmol/day, P < 0.0001), and mutation of the alpha-adducin gene (n = 161, P < 0.0001). Both before and after adjustment for covariables, continuous as well as categorical analyses revealed a significant interaction (P < or = 0.02) between plasma ouabain and urinary sodium excretion (mean 194 mmol/day) in relation to blood pressure (mean systolic blood pressure/diastolic blood pressure, 123/76 mmHg). In individuals with plasma ouabain values below the median, blood pressure increased by 2.2 mmHg systolic and 1.4 mmHg diastolic for each 50 mmol/day increment in urinary sodium excretion (P < or = 0.01). No association between blood pressure and urinary sodium excretion was found when plasma ouabain exceeded the median.


CONCLUSIONS
Plasma ouabain behaves as a blood pressure modulating factor, possibly released in response to potassium, either inhibiting the pressor effect of an excessive salt intake or counteracting the depressor action of sodium depletion.
Wang
Ji-Guang
JG
Hypertensie en Cardiovasculaire Revalidatie Eenheid, Departement voor Moleculair en Cardiovasculair Onderzoek, Katholieke Universiteit Leuven, Leuven, Belgium.
Staessen
Jan A
JA
Messaggio
Elisabetta
E
Nawrot
Tim
T
Fagard
Robert
R
Hamlyn
John M
JM
Bianchi
Giuseppe
G
Manunta
Paolo
P
D000328:Adult; D001794:Blood Pressure / Q000502:physiology*; D002148:Calmodulin-Binding Proteins / Q000235:genetics; D002298:Cardenolides; D004077:Digoxin / Q000097:blood*; D005260:Female; D005787:Gene Frequency; D006706:Homeostasis; D006801:Humans; D006973:Hypertension / Q000097:blood* / Q000235:genetics / Q000652:urine; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic; D011188:Potassium / Q000652:urine; D011897:Random Allocation; D012503:Saponins / Q000097:blood*; D012964:Sodium / Q000652:urine; D017673:Sodium Chloride, Dietary; D000099291:Adducins
D002148:Calmodulin-Binding Proteins; D002298:Cardenolides; D004077:Digoxin; D011188:Potassium; D012503:Saponins; D012964:Sodium; D017673:Sodium Chloride, Dietary; D000099291:Adducins; C034504:digoxin-like factors