Altered renal sodium handling in men with abdominal adiposity: a link to hypertension.
OBJECTIVE
Central adiposity, insulin resistance and hypertension are clearly interrelated but the mechanisms underlying this association have not been thoroughly elucidated. As renal sodium handling plays a central role in salt-sensitive forms of hypertension, we investigated the relation of renal tubular sodium handling to abdominal adiposity, blood pressure and insulin sensitivity.


METHODS
Population-based study.


METHODS
Five hundred and fifty-five untreated Olivetti male workers, aged 25-75 years.


METHODS
Olivetti factory medical centers in Pozzuoli and Marcianise (Naples, Italy)


METHODS
Anthropometric indices, serum insulin, homeostatic model assessment index of insulin sensitivity, blood pressure, fractional excretions of uric acid and exogenous lithium (as markers of renal tubular sodium handling).


RESULTS
In univariate analysis, measures of central adiposity (i.e. sagittal abdominal diameter and umbilical circumference) were directly correlated with serum insulin (P < 0.001) and blood pressure levels (P < 0.001) and inversely associated with the fractional excretions of uric acid and lithium (P = 0.01-0.001). In multiple linear regression analysis, the same anthropometric indices but not the measures of peripheral adiposity (arm circumference and tricipital skinfold thickness), were significant predictors of the fractional excretion of uric acid and lithium, independently of age, blood pressure and serum insulin levels (P = 0.01-0.001).


CONCLUSIONS
Abdominal adiposity was associated with altered renal tubular sodium handling apart from insulin resistance and high blood pressure. The data indicate that men with prevalent abdominal adiposity have an enhanced rate of tubular sodium reabsorption, mainly at proximal sites. These findings provide a possible mechanistic link between central adiposity and salt-dependent hypertension.
Strazzullo
P
P
Department of Clinical and Experimental Medicine, Unit of Clinical Genetics and Pharmacology, Hypertension and Mineral Metabolism, Federico II University of Naples Medical School, Naples, Italy. strazzul@unina.it
Barba
G
G
Cappuccio
F P
FP
Siani
A
A
Trevisan
M
M
Farinaro
E
E
Pagano
E
E
Barbato
A
A
Iacone
R
R
Galletti
F
F
D000005:Abdomen; D000273:Adipose Tissue / Q000033:anatomy & histology*; D000328:Adult; D000368:Aged; D000886:Anthropometry; D001794:Blood Pressure; D006801:Humans; D006973:Hypertension / Q000139:chemically induced; D007333:Insulin Resistance; D007668:Kidney / Q000378:metabolism*; D007684:Kidney Tubules / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D012964:Sodium / Q000378:metabolism*; D012965:Sodium Chloride
D012965:Sodium Chloride; D012964:Sodium