Influence of salt intake on the daytime-nighttime blood pressure variation in normotensive and hypertensive black subjects [Influencia da ingestao salina sobre a relacao dia-noite da pressao arterial em individuos normotensos e hipertensos de raca negra]

• Type: Another Publication in an International Scientific Journal
• Date: 2000

Authors

Damasceno, A (Author) Other; Caupers, P (Author) Other; Santos, A (Author) FCNAUP; Lobo, E (Author) Other; Sevene, E (Author) Other; Bicho, M (Author) Other; Polonia, J (Author) FMUP

Journal

Title: Revista Portuguesa de Cardiologia

Vol. 19 No. 3

Pages: 315-329

ISSN: 0870-2551

Publisher: Sociedade Portuguesa De Cardiologia

Indexing

ISI Web of Knowledge

Scopus - 10 Citations

Other information

Authenticus ID: P-007-95M

Abstract (EN): Objective: To evaluate the influence of different salt-intake regimens on the circadian rhythm of blood pressure (daytime-nighttime relationship) in normotensive and hypertensive black subjects with different patterns of salt sensitivity. Methods: Randomized, cross-over study. Twenty normotensive (NT) and 27 hypertensive (HT) black subjects were kept on a low-sodium diet (30 mmol sodium/d, LS) and on a high-sodium diet (300 mmol sodium/d, HS) for 1 week each. On the last day of each regimen, 24 hour ambulatory blood pressure monitoring was performed. Results: Eight normotensives were classified as salt-sensitive (SS), all with haptoglobin phenotypes (FeHap) 1,1 or 1,2, and 12 as salt resistant (SR), 5 with FeHap 2,2. Seventeen hypertensives were classified as SS, all with FeHap 1,1 or 1,2, and 11 as SR, 2 with FeHap 2,2. Salt sensitivity criterium was: difference > 5 mmHg of 24 h mean blood pressure from low-sodium of high sodium. The pattern of daytime-nighttime blood pressure relationship between LS and HS was only modified (respectively from dipper to non-dipper) in HT-SS, but not in NT-SS, NT-SR and HT-SR. The percentual drop in nighttime mean blood pressure was about 10% in HT-SR and in NT-SR either under LS or HS. In NT-SS, the percentual nighttime drop in mean blood pressure was lower than that of NT-RS (i.e. about 7-8%), but it was not different on LS and HS. In contrast, in HT-SS, the percentual nighttime drop in mean blood pressure on HS (6%) was significantly lower than that on IS (10%, p<0.01). In the 27 HT, but not in the NT, changes in the nocturnal drop in mean blood pressure induced by salt-restriction correlated positively with the degree of salt sensitivity (r = 0,45, p < 0,05). Conclusions: In black subjects, the pattern of nighttime-daytime blood pressure relationship appears to be modified from LS to HS diets (or vice- versa) only in SS hypertensive subjects, but neither in NT-SS nor in NT-SS and HT-SR. Only in HT-SS, but not in the other groups, salt-restriction shifts the circadian rhythm of blood pressure from a non-dipper to a dipper pattern. We conclude that in black salt-sensitive hypertensives, salt- restriction improves the circadian rhythm of blood pressure. This may have important therapeutic consequences on target organ damage associated with non-dipper patterns.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 15