Vagal Stimulation in POTS

The purpose of this study is to investigate how the electrical stimulation of a nerve in the skin of the earlobe (transcutaneous vagal nerve stimulation), alone or in combination with two medications (galantamine and pyridostigmine), affects the way the autonomic (involuntary) nervous system controls heart rhythm, symptoms on standing, and inflammatory markers in female patients with postural tachycardia syndrome (POTS). The study consists of 2 parts: a screening (1-2 study days), and 3 testing days. The study will take 5 days total and about 16 participants will be screened for the study. The investigators estimate 13 will be eligible to participate in all of the study days.

Inclusion Criteria: * Female subjects of 18-45 years, with Postural Tachycardia Syndrome (POTS) as defined by a heart rate increase ≥30 bpm from supine within 10 min of standing or head-up tilt in the absence of orthostatic hypotension, with chronic symptoms (\> 6 months), and in the absence of other acute cause of orthostatic tachycardia. * Subjects able and willing to provide informed consent Exclusion Criteria: * Pregnancy. * Medical conditions that can explain postural tachycardia (e.g., dehydration, medications). * Patients who are bedridden or chair-ridden * Subjects taking any medication known to affect autonomic function or inflammatory markers (e.g. corticosteroids) who could not discontinue them before study participation. * Conditions associated with chronic inflammatory processes which in the investigator's opinion would affect the interpretation of the results. Examples may include smoking, diabetes, BMI\>30 kg/m2, current infections or cancer. * Other factors which in the investigator's opinion would prevent the subject from completing the protocol.