Skin-specific mechanisms of body fluid regulation in hypertension
Published: 23 February 2023
Article by Sheon Samji "Skin-specific mechanisms of body fluid regulation in hypertension" published in Portland Press
Skin-specific mechanisms of body fluid regulation in hypertension
Jun Yu Chen; Khai Syuen Chew; Sheon Mary; Philipp Boder; Domenico Bagordo; Gian Paolo Rossi; Rhian M. Touyz; Christian Delles; Giacomo Rossitto
Introduction
The kidney has traditionally been regarded as the main regulator of sodium (Na+) and blood pressure (BP) homeostasis. In recent years, our understanding of these aspects expanded to include extrarenal sites of Na+ and water handling, with evidence of tissue Na+ accumulation and extracellular volume plasticity [1–3]. Peripheral tissues and in particular skin were found to act as a depot for excess Na+, with feedback mechanisms in place to ensure its drainage and ultimately whole-body Na+ balance [4,5]. Additionally, multiple systemically-acting neurohormonal axes and adaptations of the vascular system contribute to the maintenance of a steady state [6]. At odds with the abundant evidence for a systemic storage and regulation, the sole urinary route of Na+ excretion has dominated the focus of researchers for over a century. The relevance of other routes in relation to the pathophysiology and opportunity for treatment of hypertension have largely been neglected likely because of complexities regarding their investigation and the general perception of a quantitatively trivial role compared to the urinary system.
Methods
The protocol for the cross-sectional S2ALT (Skin Sodium Accumulation and water baLance in hyperTension) study was approved by the West of Scotland Research Ethics Committee 3 (ref. 18/WS/0238) and Greater Glasgow and Clyde NHS Research and Development (ref. GN18CA634). The study was conducted in compliance with the Declaration of Helsinki. All patients provided written informed consent.
Study design and protocol
Adult hypertensive patients were recruited from the Blood Pressure (BP) Clinic, Queen Elizabeth University Hospital, Glasgow, between March and July 2019. Patients were invited to participate through information leaflets and invitation letters sent 10 days before their routine clinic appointments. Exclusion criteria included pregnancy, skin conditions such as eczema or psoriasis and, for sweat collection only, implanted pacemakers or implantable cardiac defibrillators. On the day of their scheduled appointment (between 9.00 am and 4.30 pm), those consenting to take part had anthropometric (body height and weight) and routine office BP measures taken as per current guidelines [14,15] with an automated oscillometric device; pulse pressure was calculated as systolic BP−diastolic BP. For this study, uncontrolled BP was defined as office systolic BP ≥ 140 mmHg or diastolic BP ≥ 90 mmHg.
Results
A total of 90 patients, almost exclusively Caucasian (98%), were included. Males (n = 46) and females (n = 44) were equally represented. Their characteristics, notable for a high prevalence of obesity and a broad age range (21 – 86 years), are presented in Table 1. Of all participants, 74% had office BP values above 140/90 mmHg (uncontrolled hypertension), with a significantly higher prevalence in males compared with females (85% vs 62%, P = 0.015) despite a higher use of first-line antihypertensive medications. Otherwise, males and females were reasonably balanced, with the exception of the expected biochemical differences in plasma urea and creatinine [25].
First published: 23 February 2023