title: Blood pressure in relation to interactions between sodium dietary intake and renal handling.
abstract: There is abundant evidence that sodium intake is related to blood pressure. However, the relationship varies between individuals and is probably determined by renal sodium handling. We investigated clinic and ambulatory blood pressure in relation to interactions between sodium dietary intake and renal handling, as assessed by 24-hour urinary sodium excretion and endogenous lithium clearance, respectively. We calculated fractional excretion of lithium and fractional distal reabsorption rate of sodium, as markers of proximal and distal sodium handling, respectively. The 766 subjects included 379 men and 478 ambulatory hypertensive patients. They were never treated (n=697) or did not take antihypertensive medication for ≥2 weeks (n=69). In adjusted analyses, none of the associations of urinary sodium excretion, fractional excretion of lithium, and fractional distal reabsorption rate of sodium with clinic or ambulatory blood pressure were statistically significant (P≥0.09). However, there was significant (P=0.01) interaction between urinary sodium excretion and fractional excretion of lithium in relation to nighttime diastolic blood pressure. In tertile 3 but not tertiles 1 and 2 of fractional excretion of lithium, nighttime diastolic pressure was positively associated with urinary sodium excretion (P=0.03). However, nighttime diastolic pressure was higher in tertile 1 than tertile 3 of fractional excretion of lithium (+2.0 mm Hg; P=0.01), especially in the bottom tertile of urinary sodium excretion (+4.9 mm Hg; P<0.001). Similar trends were observed for nighttime systolic pressure and clinic and 24-hour diastolic pressure. In conclusion, sodium dietary intake and proximal tubular handling interact to be associated with blood pressure.
authors: The Shanghai Institute of Hypertension, Ruijin 2nd Rd 197, Shanghai 200025, China. jiguangwang@aim.com.
authors: Jun
authors: J
authors: Zou
authors: Yan
authors: Y
authors: Li
authors: Chong-Huai
authors: CH
authors: Yan
authors: Fang-Fei
authors: FF
authors: Wei
authors: Lu
authors: L
authors: Zhang
authors: Ji-Guang
authors: JG
authors: Wang
mesh_terms: D000328:Adult; D000368:Aged; D001794:Blood Pressure / Q000502:physiology*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000097:blood / Q000503:physiopathology* / Q000652:urine; D007668:Kidney / Q000378:metabolism / Q000502:physiology* / Q000503:physiopathology; D008094:Lithium / Q000097:blood / Q000378:metabolism* / Q000652:urine; D008297:Male; D008875:Middle Aged; D012964:Sodium / Q000097:blood / Q000378:metabolism* / Q000652:urine; D012982:Sodium, Dietary; D011795:Surveys and Questionnaires
chemical_list: D012982:Sodium, Dietary; D008094:Lithium; D012964:Sodium
keywords: blood pressure; kidney tubules, proximal; lithium; sodium