[OP.8B.09] SODIUM SENSITIVITY AND INVERSE SODIUM SENSITIVITY IN NORMOTENSIVE AND HYPERTENSIVE INDIVIDUALS

• Published in: Journal of hypertension Vol. 35 Suppl 2 - ESH 2017 Abstract Book; no. Supplement 2; p. e89
• Main Authors: Castiglioni, P, Parati, G, Lazzeroni, D, Bini, M, Faini, A, Brambilla, L, Brambilla, V, Coruzzi, P
• Format: Journal Article
• Language: English
• Published: Copyright Wolters Kluwer Health, Inc. All rights reserved 01-09-2017
• ISSN: 0263-6352; 1473-5598
• DOI: 10.1097/01.hjh.0000523206.50318.bb

OBJECTIVETraditionally, individuals are dichotomously classified as Sodium Sensitive (SS), if mean blood pressure (BP) is higher after a high-salt than a low-salt diet, or Sodium Resistant (SR) otherwise. Recently, Felder et al. (Curr Opin Nephrol Hypertens, 2013) observed subjects with higher mean BP after the low-salt diet compared with the high-salt diet in a mixed population of normotensives and hypertensives, introducing the class of Inverse Sodium Sensitive (ISS) individuals. Our aim is to compare normotensives and hypertensives following this new classification.
DESIGN AND METHOD71 normotensive (No) volunteers (age 27.4 +5.8 yrs, BMI 22.2 +2.7 kg/m, M +SD) and 46 hypertensive (Hy) volunteers (45.0 +7.6 yrs, 24.5 +2.9 kg/m) underwent high-salt and low-salt diets (30 vs. 200 mmol NaCl/day), each of 5-day duration. Brachial BP was measured at the end of each diet and the Sodium Sensitivity Index (SS-Index) calculated as ratio between difference in mean BP and difference in 24-hour urinary sodium excretion rate. We classified participants as ISS if SSIndex was <−15 mmHg/(mol × day), as SS if SS-Index was > 15, as SR otherwise. We compared differences between high- and low-salt diets in Systolic BP (SBP), Diastolic BP (DBP) and Heart Rate (HR) by ANOVA.
RESULTSThe 3 classes were homogeneously distributed in the No group (ISS = 41%; SR = 35%; SS = 24%) while SS individuals prevailed in the Hy group (ISS = 7%; SR = 22%; SS = 72%, p < 0.01 comparing No with Hy by Chi-square test). The figure shows m+sem of the difference between high- and low-salt diets (δ) stratified by class of sodium sensitivity. Hy and No groups had the same trend for DBP (factors significanceclass p < 0.01; group p = 0.92; interaction p = 0.40). This was not the case for SBP (class p < 0.01; group p < 0.01; interaction p = 0.05), with greater SBP increase in SS individuals of Hy group. The high-salt diet decreased HR without significant differences among classes or between groups (class p = 0.08; group p = 0.34; interaction p = 0.76).(Figure is included in full-text article.)
CONCLUSIONSISS individuals are common among normotensives and rare among hypertensives. SS hypertensives have greater pressor response to salt than SS normotensive but for Systolic BP only, not for Diastolic BP.