Water and Electrolytes Content in HYpertension (WHYSKI) in the SKIn

Background. Given the key role of Na+ in the pathophysiology of HT, this study will test the hypothesis that in PA, which is the paradigm of salt-dependent hypertension, the skin, Na+, K+ and water content is altered and these alterations are corrected by surgical cure of PA with video-laparoscopic adrenalectomy. The investigators will use skin biopsies to directly examine the content of Na+, K+, water, and the lympho-angiogenetic transcription factor Tonicity Enhancing Binding Protein (TonEBP) mRNA in the skin, an important reservoir of body Na+, in primary aldosteronism (PA), the prototype of salt-dependent hypertension. Methods. The investigators will measure Na+, K+, and water content (by chemical-physical methods) and TonEBP mRNA copy number (by droplet digital PCR) in skin biopsies from a sex-mixed cohort of consecutive consenting patients with unilateral PA treated with a mineralocorticoid receptor antagonist (MRA), before surgery, at doses that correct hypokalemia and HT in order to refer them for surgery with normokalemia and controlled high blood pressure, as per protocol at our institution. The participants will be reassessed in an identical way again after surgical cure. The investigators expect the dry weight (DW) of the skin specimen obtained at surgery to be significantly higher than at follow-up and to correlate positively with skin Na+, K+, and water content. Hence, if these predictions will be verified, the skin cations and water content will need to be DW-adjusted in order to provide meaningful comparisons across specimen obtained at different time points. The investigators expect the TonEBP mRNA copy number to be markedly overexpressed compared to healthy subjects. The WHYSKI study will provide solid knowledge of the skin Na+, K+ and water content in patients with arterial salt-dependent hypertension due to PA, PH, and on the effect of cure of the hyperaldosteronism on these variables. The investigators also expect to gather novel knowledge on the molecular and cellular mechanisms involved in the regulation of the content on Na+, K+ and water in a compartment as the skin interstitium that has been largely neglected thus far.