{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,22]],"date-time":"2026-09-22T00:17:34Z","timestamp":1790036254925,"version":"4.0.1"},"reference-count":44,"publisher":"American Physiological Society","issue":"6","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["American Journal of Physiology-Heart and Circulatory Physiology"],"published-print":{"date-parts":[[2003,12]]},"abstract":"<jats:p>\n                    Postural tachycardia syndrome (POTS) is defined by orthostatic intolerance associated with abnormal upright tachycardia. Some patients have defective peripheral vasoconstriction and increased calf blood flow. Others have increased peripheral arterial resistance and decreased blood flow. In 14 POTS patients (13\u201319 yr) evenly subdivided among low-flow POTS (LFP) and high-flow POTS (HFP) we tested the hypothesis that myogenic, venoarteriolar, and reactive hyperemic responses are abnormal. We used venous occlusion plethysmography to measure calf venous pressure and blood flow in the supine position and when the calf was lowered by 40 cm to evoke myogenic and venoarteriolar responses and during venous hypertension by 40-mmHg occlusion to evoke the venoarteriolar response. We measured calf reactive hyperemia with plethysmography and cutaneous laser-Doppler flowmetry. Baseline blood flow in LFP was reduced compared with HFP and control subjects (0.8 \u00b1 0.2 vs. 4.4 \u00b1 0.5 and 2.7 \u00b1 0.4 ml \u00b7 min\n                    <jats:sup>\u20131<\/jats:sup>\n                    \u00b7 100 ml\n                    <jats:sup>\u20131<\/jats:sup>\n                    ) but increased during leg lowering (1.2 \u00b1 0.5 ml \u00b7 min\n                    <jats:sup>\u20131<\/jats:sup>\n                    \u00b7 100 ml\n                    <jats:sup>\u20131<\/jats:sup>\n                    ) while decreasing in the others. Baseline peripheral arterial resistance was increased in LFP and decreased in HFP compared with control subjects (39 \u00b1 13 vs. 15 \u00b1 3 and 22 \u00b1 5 mmHg \u00b7 ml\n                    <jats:sup>\u20131<\/jats:sup>\n                    \u00b7 100 ml \u00b7 min) but decreased to 29 \u00b1 13 mmHg \u00b7 ml\n                    <jats:sup>\u20131<\/jats:sup>\n                    \u00b7 100 ml \u00b7 min in LFP during venous hypertension. Resistance increased in the other groups. Maximum calf hyperemic flow and cutaneous flow were similar in all subjects. The duration of hyperemic blood flow was curtailed in LFP compared with either control or HFP subjects (plethysmographic time constant = 20 \u00b1 2 vs. 29 \u00b1 4 and 28 \u00b1 4 s; cutaneous time constant = 60 \u00b1 25 vs. 149 \u00b1 53 s in controls). Local blood flow regulation in low-flow POTS is impaired.\n                  <\/jats:p>","DOI":"10.1152\/ajpheart.00429.2003","type":"journal-article","created":{"date-parts":[[2015,3,3]],"date-time":"2015-03-03T15:15:00Z","timestamp":1425395700000},"page":"H2749-H2756","source":"Crossref","is-referenced-by-count":59,"title":["Local vascular responses affecting blood flow in postural tachycardia syndrome"],"prefix":"10.1152","volume":"285","author":[{"given":"Julian M.","family":"Stewart","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Marvin S.","family":"Medow","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Leslie D.","family":"Montgomery","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"24","reference":[{"key":"REF1","doi-asserted-by":"publisher","DOI":"10.1113\/jphysiol.1902.sp000911"},{"key":"REF2","doi-asserted-by":"publisher","DOI":"10.1111\/j.1469-7793.1997.463bh.x"},{"key":"REF3","doi-asserted-by":"publisher","DOI":"10.1161\/01.HYP.33.6.1453"},{"key":"REF4","doi-asserted-by":"publisher","DOI":"10.1113\/jphysiol.2001.013060"},{"key":"REF5","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1996.81.4.1807"},{"key":"REF6","doi-asserted-by":"crossref","unstructured":"Folkow B\n                      .\n                      Hypertensive structural changes in systemic precapillary resistance vessels: how important are they for in vivo haemodynamics?\n                      J Hypertens\n                      13\n                      : 1546\u20131559, 1995.","DOI":"10.1097\/00004872-199512010-00007"},{"key":"REF7","doi-asserted-by":"publisher","DOI":"10.7326\/0003-4819-104-3-298"},{"key":"REF8","doi-asserted-by":"publisher","DOI":"10.1152\/japplphysiol.00817.2001"},{"key":"REF9","doi-asserted-by":"publisher","DOI":"10.1161\/01.CIR.98.20.2154"},{"key":"REF10","doi-asserted-by":"publisher","DOI":"10.1111\/j.1469-7793.1998.611bt.x"},{"key":"REF11","doi-asserted-by":"crossref","unstructured":"Gniadecka M\n                      , Gniadecki R, Serup J, and Sondergaard J.\n                      Impairment of the postural venoarteriolar reflex in aged individuals.\n                      Acta Derm Venereol\n                      74\n                      : 194\u2013196, 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PA\n                      , Opfer-Gehrking TL, Textor SC, Benarroch EE, Shen WK, Schondorf R, Suarez GA, and Rummans TA.\n                      Postural tachycardia syndrome (POTS).\n                      Neurology\n                      45\n                      : S19\u2013S25, 1995."},{"key":"REF25","doi-asserted-by":"publisher","DOI":"10.1111\/j.1748-1716.1993.tb09485.x"},{"key":"REF26","doi-asserted-by":"publisher","DOI":"10.1177\/000331979804901004"},{"key":"REF27","doi-asserted-by":"publisher","DOI":"10.1111\/j.1748-1716.1964.tb02940.x"},{"key":"REF28","doi-asserted-by":"publisher","DOI":"10.1212\/WNL.39.11.1490"},{"key":"REF29","doi-asserted-by":"publisher","DOI":"10.3109\/03091909009009955"},{"key":"REF30","unstructured":"Richardson DR\n                      and Shepherd S.\n                      Separate effects of gravity and venous pressure on regional and capillary blood flows in the human finger.\n                      Microcirc Endothelium Lymphatics\n                     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1989."},{"key":"REF31","doi-asserted-by":"publisher","DOI":"10.4065\/74.11.1106"},{"key":"REF32","doi-asserted-by":"publisher","DOI":"10.1212\/WNL.43.1_Part_1.132"},{"key":"REF33","doi-asserted-by":"publisher","DOI":"10.1111\/j.1748-1716.1981.tb06738.x"},{"key":"REF34","doi-asserted-by":"publisher","DOI":"10.1093\/cvr\/16.7.357"},{"key":"REF35","doi-asserted-by":"publisher","DOI":"10.1161\/01.CIR.0000016348.55378.C4"},{"key":"REF36","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.2001.91.4.1723"},{"key":"REF37","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.2000.89.4.1505"},{"key":"REF38","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.2001.90.6.2025"},{"key":"REF39","doi-asserted-by":"publisher","DOI":"10.3109\/10739689509146775"},{"key":"REF40","doi-asserted-by":"publisher","DOI":"10.1161\/01.CIR.90.5.2285"},{"key":"REF41","doi-asserted-by":"publisher","DOI":"10.1016\/S1566-0702(00)00205-8"},{"key":"REF42","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.2001.91.1.522"},{"key":"REF43","doi-asserted-by":"publisher","DOI":"10.1046\/j.1365-201X.1997.573344000.x"},{"key":"REF44","doi-asserted-by":"publisher","DOI":"10.1152\/japplphysiol.00254.2003"}],"container-title":["American 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