Objective: It is now established that “dippers” whose blood pressure (BP) falls at night have lower cardiovascular risks than nondippers without nocturnal BP fall. Our previous study on the middle-aged general population in Korea indicated increased 24-hour urinary (24U) sodium excretion was associated with increased nighttime BPs. Therefore, we further analyzed the association of salt intakes estimated by 24U analysis with dipping in nocturnal BP and heart rate.Design and Method:
Design and method: In the rural area in South Korea 218 subjects aged 30 to 59 years were measured with casual and ambulatory BP monitoring (ABPM) (TM2430, A&D, Tokyo, Japan) and their 24U samples collected by aliquot cups were analyzed.Results:
For both ABPM and 24U analyses, 148 subjects, aged 47.4 ± 8.3 years in average and female rates 57.4%, were accepted for data analysis by the 24U creatinine equation. Salt intake, previously proven to be associated with nighttime systolic and diastolic BP but not with casual and daytime BP, was further analyzed to be significantly inversely associated not only with nocturnal dipping in systolic and diastolic BP (P < 0.01, 0.001), but also in heart rate (P < 0.01). Correlations of the dipping of systolic (Fig) and diastolic BPs with heart rate were significant (P < 0.001, 0.01).Conclusions:
Conclusion: Higher salt intake attenuates dipping not only in BP but also in heart rate. Nocturnal heart rate monitoring, more easily available than ABPM, may be useful for detecting nocturnal BP rise and salt sensitivity related to cardiovascular risks.