POTS-FLOW: Interplay Between Gut Hormones and Autonomic Postprandial Blood Flow Regulation in Patients With POTS

Inclusion Criteria POTS patients: * Previously diagnosed with POTS in tilt test or active stand-test (either newly diagnosed within last 3 months or in new tilt test/active stand test during screenings visit) * Reproducible orthostatic intolerance with raise in HR on \>30 bpm when standing within 10 minutes of change of supine to standing in age \>19 years or \>40 bpm in age 18-19 years. * POTS symptoms/orthostatic intolerance * Age 18-50 * Waist ratio \<180 cm Exclusion Criteria: * Chronic illness * Metallic implants * Above 10 alcoholic drinks or week or substance abuse * Other types of sinus tachycardia or heart disease * Liverenzymes two times above normal values * Decreased kidney function eGFR \<90 or elevated kreatinkinasis * Thyroid disease or TSH out of reference * Uncontrollable low or high blood pressure * Blood vessels that cannot be visualized on MR * Any disease that might influence the health of the participant during the study or participants that receives medicine that cannot be paused for 36 hours Inclusion Criteria: * Age 18-50 * Waist ratio \<180 cm * Matched a POTS patient in age, sex and BMI Exclusion Criteria: * Chronic illness * Metallic implants * Above 10 alcoholic drinks or week or substance abuse * POTS; other types of sinus tachycardia or heart disease * Liverenzymes two times above normal values * Decreased kidney function eGFR \<90 or elevated kreatinkinasis * Thyroid disease or TSH out of reference * Uncontrollable low or high blood pressure, Orthostatic hypotension * Blood vessels that cannot be visualized on MR * Any disease that might influence the health of the participant during the study or participants that receives medicine that cannot be paused for 36 hours