BLOOD PRESSURE VARIABILITY IN PATIENTS WITH PARKINSON’S DISEASE IS ASSOCIATED WITH ALTERED WATER BALANCE: A POTENTIAL ROLE FOR THE ADH AND APELIN SYSTEMS

Objective: Cardiovascular autonomic dysfunction is an important non-motor phenotype of Parkinson’s disease (PD). It consists primarily of orthostatic hypotension (OH), which is often associated with supine hypertension (SH), making it therapeutically challenging. Apelin system has recently been identified as a key player in water balance, which is thought to play a role in blood pressure (BP) regulation. Thus, our aim was to evaluate the Antidiuretic Hormone (ADH) and Apelin systems in relation to BP profile in untreated and treated PD patients. Design and method: A total of 31 PD individuals were divided into three groups according to the Ambulatory-Monitoring-Blood-Pressure (ABPM) profile obtained at two different time points: patients with OH (n=7), patients with both OH and SH (SH_OH, n=16), and treatment-naïve PD patients without BP alterations (n=9). Control group included 21 healthy age-matched subjects. Day and night periods were defined according to the time actually spent awake and asleep, respectively. SH_OH subjects were given Eprosartan (n=7), Nicardipine (n=4) or Nitrates (n=5) for 3 weeks and the ABPM was repeated at the end of treatment. Morning plasma levels of Copeptin, Apelin and Elabela were assessed by ELISA before and after antihypertensive treatment. Results: As expected, SH_OH patients had higher nocturnal BP values compared to the other groups (p<0.0001), while daytime BP levels were lower in both SH_OH and OH groups (p<0.01). After 3-week treatment, Eprosartan significantly reduced nocturnal BP while increasing daytime BP (p<0.05). Nicardipine induced a similar reduction in nocturnal BP (p<0.05), but without altering diurnal values. No effect was seen with Nitrate administration. Interestingly, before treatment, Apelin and Elabela were significantly reduced in SH_OH patients, whereas Copeptin levels were higher in both SH_OH and OH groups. Eprosartan administration increased Apelin, Elabela and Copeptin levels (p<0.01), while Nitrates reduced Copeptin (p<0.01). Conclusions: Altered day-night water balance may affect BP profile in PD patients, with high Copeptin and low Apelin and Elabela levels possibly explaining supine hypertension. Treatment with Eprosartan improved BP profile along with significant increases in Apelin and Elabela levels, paving the way for further studies on water metabolism in BP regulation and its variability.