Effects of dietary salt restriction on home blood pressure in diabetic patients with excessive salt intake: a pilot study

Observational cohort studies suggest that severe salt restriction increases cardiovascular morbidity/mortality, and the relationship between cardiovascular morbidity and dietary salt intake resembles a J-shaped curve. A high salt diet exaggerates sympathetic nerve activity (SNA) and arterial blood pressure (ABP) responses to several cardiovascular reflexes in salt-resistant animals. This study assessed whether salt restriction also exaggerates cardiovascular reflex responses and sensitizes central autonomic networks. To test this hypothesis, male Sprague-Dawley rats were fed low (0.01% NaCl), normal (0.1% NaCl), and high (4.0% NaCl) salt diet for 14-21 days. Baseline mean ABP was not different across groups (low: 104±4, normal: 107±4, high: 107±4mmHg). Activation of sciatic afferents (1ms pulse, 500uA, 5s duration, 2-20Hz) produced significantly greater increases in renal SNA (5Hz; low: 196±12, normal: 136±9, high: 177±8%, n=8, P<0.05) and ABP (5Hz; low: 29±3, normal: 16±1, high: 24±2 mmHg, n=8, P<0.05) of rats fed low and high versus normal NaCl diets. Activation of the aortic depressor nerve (2ms pulse, 500uA, 15s duration, 2-20Hz) produced significantly greater decreases in renal SNA (5Hz; low: -55±9, normal: -34±8, high: -63±13%, n=7-8, P<0.05) and ABP (5Hz; low: -31±3, normal: -15±5, high: -32±5 mmHg, n=7-8, P<0.05) of rats fed low and high versus normal NaCl diets. To test whether dietary salt intake sensitized central sympathetic circuits, microinjection of L-glutamate (0.1-1nmol, 30nL) in the rostral ventrolateral medulla produced significantly greater increases in renal SNA (0.1nmol; low: 212±15, normal: 149±8, high: 183±17%, n=7-8, P<0.05) and ABP (0.1Hz; low: 20±2, normal: 12±2, high: 22±2 mmHg, n=7-8, P<0.05) of rats fed low and high versus normal NaCl diets. Finally, rats fed low or high NaCl versus normal NaCl diets displayed exaggerated cardiovascular responses to cage switch or mild restraint and increased 24-h blood pressure variability. The present findings show that severe salt restriction and excess dietary salt intake exaggerate sympathetic and cardiovascular responses, and may be explained by a parallel change in the sensitivity of central autonomic networks to resemble a J-shaped curve.

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Effects of dietary salt restriction with or without cilazapril on office and ambulatory blood pressure

Atherosclerosis ◽

10.1016/0021-9150(94)94092-4 ◽

1994 ◽

Vol 109 (1-2) ◽

pp. 273

Author(s):

R. Rauramaa ◽

M. Korhonen ◽

H. Litmanen ◽

L. Niskanen ◽

M. Uusitupa

Keyword(s):

Blood Pressure ◽

Ambulatory Blood Pressure ◽

Dietary Salt ◽

Salt Restriction ◽

Dietary Salt Restriction

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Both Dietary Salt Restriction and Excess Dietary Salt Intake Exaggerate Cardiovascular Reflex Responses to Activation of the Sciatic Afferents, Aortic Depressor Nerve, and Vagal Afferents

The FASEB Journal ◽

10.1096/fasebj.2019.33.1_supplement.850.15 ◽

2019 ◽

Vol 33 (S1) ◽

Author(s):

Pedro Lourenco Katayama ◽

Megan M Wenner ◽

William B Farquhar ◽

Kirsteen N Browning ◽

Sean D Stocker

Keyword(s):

Salt Intake ◽

Vagal Afferents ◽

Dietary Salt ◽

Salt Restriction ◽

Dietary Salt Intake ◽

Reflex Responses ◽

Aortic Depressor Nerve ◽

Cardiovascular Reflex ◽

Dietary Salt Restriction

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Evaluation of the efficacy of simplified nutritional instructions from physicians on dietary salt restriction for patients with type 2 diabetes mellitus consuming excessive salt: protocol for a randomized controlled trial

Trials ◽

10.1186/s13063-019-3864-8 ◽

2019 ◽

Vol 20 (1) ◽

Author(s):

Emi Ushigome ◽

Chikako Oyabu ◽

Makoto Shiraishi ◽

Nobuko Kitagawa ◽

Aya Kitae ◽

...

Keyword(s):

Diabetes Mellitus ◽

Type 2 Diabetes ◽

Type 2 Diabetes Mellitus ◽

Salt Intake ◽

Intervention Group ◽

Control Group ◽

Dietary Salt ◽

Salt Restriction ◽

Dietary Salt Restriction

Abstract Background Hypertension is present in more than 50% of patients with type 2 diabetes mellitus. Dietary salt restriction is recommended for the management of high blood pressure. Instructions on dietary salt restriction, provided by a dietitian, have been shown to help patients reduce their salt intake. However, appointments for the dietitians in hospitals are often already fully booked, making it difficult for patients to receive instructions on the same day as the outpatient clinic visit. Aim The aim of this trial is to test a new intervention to assess whether guidance on dietary salt restriction provided by physicians during outpatient visits is effective in reducing salt intake in patients with type 2 diabetes mellitus who have an excessive salt intake. Methods In this unblinded randomized controlled trial (RCT), a total of 200 patients, male or female, aged between 20 and 90 years, who have type 2 diabetes mellitus and consume excessive salt will be randomly assigned to two groups: an intervention group and a control group. In addition to being given routine treatment, participants in the intervention group will be given individual guidance on restricting their dietary salt intake by a physician upon enrollment. The control group will only be given routine treatment. Participants will be followed up for 24 weeks. The primary outcome will be dietary salt intake, which will be assessed at baseline and at 8, 16, and 24 weeks. The secondary outcomes, including body weight, body mass index, hemoglobin A1c level, blood pressure, blood glucose level, serum lipid profile, and urinary albumin excretion level, will be assessed at baseline and at 8, 16, and 24 weeks. Discussion The results of this RCT have the potential to provide a simple and novel clinical approach to reduce salt intake among patients with type 2 diabetes, making regular visits to their physician, in outpatient facilities. This protocol will contribute to the literature because it describes a practical intervention that has not been tested previously, and it may serve as guidance to other researchers interested in testing similar interventions. Trial registration University Hospital Medical Information Network (UMIN), UMIN000028809. Registered retrospectively on 24 August 2017. http://www.umin.ac.jp.

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