Higashi Y, Oshima T, Ozono R, Nakano Y, Matsuura H, Kambe M, Kajiyama G
Nocturnal blood pressure decline is attenuated by NaCl loading in salt-sensitive patients with essential hypertension
50th Annual Fall Conference AHA Council for High Blood Pressure Research
Hypertens (Sep) 28:547 1996

A subset of hypertensive subjects is especially prone to the BP elevating effects of increasing amounts of dietary sodium. It is however not known if increased dietary sodium also blunts the usual decline in sleep blood pressure.

The authors studied 26 salt-sensitive (SS) patients and 38 salt-resistant (SR) patients on two levels of sodium intake (50 mmol/day and 340 mmol/day) using ambulatory blood pressure monitoring. All patients followed each level of sodium intake for one week. Dipper status was defined in this study as mean BP change of more than 10% from day to night and nondipper as less than 10%. SS was defined as a mean BP change of greater than 10% from low to high sodium intake.

By definition, the SS patients had higher mean BP during the high salt intake for both daytime and nighttime, while the mean BP was similar during the two periods in the SR group. The proportion of non-dippers was higher in the SS patients than in the SR patients during the high sodium intake (15/26 vs 10/38, chi-square 6.4, p =.02).

Comment: At baseline in this study, there are more nondippers in the SS group compared to the SR group, which reflect some selection bias. If these findings are confirmed, then salt sensitivity may confer additional hidden dangers during the sleep period if subjects are on a high sodium intake. The results of this study when published in detail will make interesting reading. (George Mansoor, M.D., University of Connecticut)

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50th Annual Fall Conference AHA Council for High Blood Pressure Research
H: Pathophysiology : Salt (sodium, chloride) sensitivity
H: Exam and lab tests : Ambulatory monitoring