What is the clinical evidence from this study?

Study design: Observational. Population: Insulin-dependent diabetes mellitus (IDDM). Intervention: Dietary sodium restriction vs. 250 mmol/day sodium diet and healthy controls. Primary outcome: Forearm vascular resistance (FVR) response to lower body negative pressure (LBNP) on 250 mmol sodium diet.

August 1, 1995

Sympathetic vasoconstrictive responses to high- and low-sodium diets in diabetic and normal subjects

Key Result

In subjects with uncomplicated IDDM, dietary sodium restriction to 20 mmol/day normalized the attenuated forearm vascular response to lower body negative pressure and venous hyperresponsiveness to norepinephrine.

Study Design

Type

Observational

Structured PICO

Does dietary sodium restriction normalize sympathetic vasoconstrictive responses in subjects with uncomplicated insulin-dependent diabetes mellitus?

Population

Subjects with uncomplicated insulin-dependent diabetes mellitus (IDDM) with disease duration < 5 years (n=9) and normal control subjects.

Intervention

Dietary sodium restriction (20 mmol/day) compared to a high-sodium diet (250 mmol/day), with physiological testing including lower body negative pressure (LBNP), cold pressor test (CPT), and local norepinephrine infusion.

Comparator

Normal control subjects undergoing the same dietary and physiological testing protocols.

Outcome

Plasma norepinephrine (PNE) and forearm vascular resistance (FVR) responses to cardiopulmonary baroreceptor unloading by lower body negative pressure (LBNP).surrogate

Dietary sodium restriction can normalize hyperresponsive peripheral vasculature and attenuated forearm vascular responses to sympathetic stimulation in early insulin-dependent diabetes mellitus.

Main Result

Absolute Event Rate: 4.3% vs 11.56%

Abstract

Uncomplicated insulin-dependent diabetes mellitus (IDDM) is associated with a suppressed reflex response to sympathetic nervous system (SNS) stimulation and an enhanced pressor response to catecholamines. This study examined the SNS in subjects with IDDM (duration < 5 yr, n = 9) to determine the responsible mechanism within the cardiopulmonary baroreflex arc and the role played by extracellular fluid volume (ECFV) expansion. The reflex arc was tested by examining the plasma norepinephrine (PNE) and forearm vascular (FVR) responses to 60 min of cardiopulmonary baroreceptor unloading by lower body negative pressure (LBNP) at -15 mmHg. The effector limb was tested by measuring the PNE, FVR, and mean arterial pressure (MAP) response to the cold pressor test (CPT). The postganglionic neuroeffector junction was tested by measuring the venoconstrictive response to local norepinephrine infusion. ECFV was varied by altering dietary sodium. In IDDM subjects on a 250 mmol sodium diet, PNE and FVR responses to LBNP (delta PNE = 0.15 +/- 0.05; delta FVR = 4.3 +/- 1.2) were attenuated compared with controls (delta PNE = 0.36 +/- 0.23; delta FVR = 11.56 +/- 2.72). MAP and FVR responses to the CPT were intact (delta MAP = 9.74 +/- 1.9; delta FVR = 7.02 +/- 3.11) compared with controls (delta MAP = 10.74 +/- 2.69; delta FVR = 8.26 +/- 2.94), but the PNE response was attenuated. The peripheral vasculature was hyperresponsive to norepinephrine infusion in IDDM subjects mean effective dose (ED50) = 57 +/- 10 ng/min compared with controls (ED50 = 133 +/- 30 ng/min). Sodium restriction (20 mmol/day) normalized the FVR response to LBNP and the venous response to norepinephrine infusion. The PNE response both to LBNP and the CPT remained attenuated.(ABSTRACT TRUNCATED AT 250 WORDS)

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