{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,30]],"date-time":"2026-09-30T08:46:33Z","timestamp":1790757993378,"version":"4.1.0"},"reference-count":57,"publisher":"American Physiological Society","issue":"2","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["American Journal of Physiology-Heart and Circulatory Physiology"],"published-print":{"date-parts":[[2005,2]]},"abstract":"<jats:p> Head-down bed rest changes the values of many cardiovascular and endocrine variables and also elicits significant hypovolemia. Because previous studies had not controlled for hypovolemia, it is unknown whether the reported changes were primary effects of bed rest or secondary effects of bed rest-induced hypovolemia. We hypothesized that restoring plasma volume with salt tablets and water after 12 days of head-down bed rest would result in an absence of hemodynamic and endocrine changes and a reduced incidence of orthostatic hypotension. In 10 men, we measured changes from pre-bed-rest to post-bed-rest in venous and arterial pressures; heart rate; stroke volume; cardiac output; vascular resistance; plasma norepinephrine, epinephrine, vasopressin, renin activity (PRA), and aldosterone responses to different tilt levels (0\u00b0, \u221210\u00b0, 20\u00b0, 30\u00b0, and 70\u00b0); and plasma volume and platelet \u03b1<jats:sub>2<\/jats:sub>- and lymphocyte \u03b2<jats:sub>2<\/jats:sub>-adrenoreceptor densities and affinities (0\u00b0 tilt only). Fluid loading at the end of bed rest restored plasma volume and resulted in the absence of post-bed-rest orthostatic hypotension and changes in supine hemodynamic and endocrine variables. Fluid loading did not prevent post-bed-rest increases in \u03b2<jats:sub>2<\/jats:sub>-adrenoreceptor density or decreases in the aldosterone-to-PRA ratio ( P = 0.05 for each). Heart rate, epinephrine, and PRA responses to upright tilt after bed rest were increased ( P &lt; 0.05), despite the fluid load. These results suggest that incidents of orthostatic hypotension and many of the changes in supine hemodynamic and endocrine variables in volume-depleted bed-rested subjects occur secondarily to the hypovolemia. Despite normovolemia after bed rest, \u03b2<jats:sub>2<\/jats:sub>-adrenoreceptors were upregulated, and heart rate, epinephrine, and PRA responses to tilt were augmented, indicating that these changes are independent of volume depletion. <\/jats:p>","DOI":"10.1152\/ajpheart.00220.2004","type":"journal-article","created":{"date-parts":[[2004,10,15]],"date-time":"2004-10-15T00:14:51Z","timestamp":1097799291000},"page":"H839-H847","source":"Crossref","is-referenced-by-count":52,"title":["Plasma volume restoration with salt tablets and water after bed rest prevents orthostatic hypotension and changes in supine hemodynamic and endocrine variables"],"prefix":"10.1152","volume":"288","author":[{"given":"Wendy W.","family":"Waters","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Steven H.","family":"Platts","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Brett M.","family":"Mitchell","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Peggy A.","family":"Whitson","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Janice V.","family":"Meck","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"24","reference":[{"key":"R1","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1999.87.5.1614"},{"key":"R2","unstructured":"Beck L, Baisch F, Gaffney FA, Buckey JC, Arbeille PH, Patat F, Ten Harkel ADJ, Hillebrecht A, Schulz H, Karemaker JM, Meyer M, and Blomqvist CG. Cardiovascular response to lower body negative pressure before, during, and after 10 days head-down tilt bedrest. Acta Physiol Scand 144: 43\u201352, 1992."},{"key":"R3","doi-asserted-by":"publisher","DOI":"10.1016\/0165-6147(87)90108-8"},{"key":"R4","doi-asserted-by":"publisher","DOI":"10.1126\/science.3006250"},{"key":"R5","doi-asserted-by":"crossref","unstructured":"Brown JE, McLeod AA, and Shand DG. In support of cardiac chronotropic \u03b22-adrenoceptors. Am J Cardiol 57: 11F\u201316F, 1986.","DOI":"10.1016\/0002-9149(86)90882-9"},{"key":"R6","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1996.81.1.7"},{"key":"R7","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1995.79.2.623"},{"key":"R8","doi-asserted-by":"publisher","DOI":"10.1097\/00003246-199310000-00023"},{"key":"R9","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1990.68.4.1458"},{"key":"R10","doi-asserted-by":"publisher","DOI":"10.1152\/ajpregu.1994.266.6.R1962"},{"key":"R11","doi-asserted-by":"publisher","DOI":"10.1007\/BF02267820"},{"key":"R12","doi-asserted-by":"publisher","DOI":"10.1152\/ajpregu.1997.273.1.R93"},{"key":"R13","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1994.77.5.2134"},{"key":"R14","doi-asserted-by":"publisher","DOI":"10.1210\/jcem-63-4-847"},{"key":"R15","doi-asserted-by":"crossref","unstructured":"Freudenthaler SM, Schenck T, Lucht I, and Gleiter CH. Fenoterol stimulates human erythropoietin production via activation of the renin-angiotensin system. Br J Clin Pharmacol 48: 631\u2013634, 1999.","DOI":"10.1046\/j.1365-2125.1999.00059.x"},{"key":"R16","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1996.81.5.2134"},{"key":"R17","doi-asserted-by":"publisher","DOI":"10.1016\/S0306-4530(02)00046-X"},{"key":"R18","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1995.78.3.1023"},{"key":"R19","doi-asserted-by":"publisher","DOI":"10.1161\/01.RES.65.3.546"},{"key":"R20","unstructured":"Hinghofer-Szalkay HG, Vigas M, Sauseng-Fellegger G, Konig EM, Lichardus B, and Jezova D. Head-up tilt and lower body suction: comparison of hormone responses in healthy men. Physiol Res 45: 369\u2013378, 1996."},{"key":"R21","doi-asserted-by":"publisher","DOI":"10.1152\/ajpregu.2000.279.6.R2189"},{"key":"R22","doi-asserted-by":"publisher","DOI":"10.1016\/S0304-3940(00)00804-1"},{"key":"R23","doi-asserted-by":"publisher","DOI":"10.1152\/ajpheart.00965.2002"},{"key":"R24","doi-asserted-by":"publisher","DOI":"10.1152\/ajpheart.00535.2001"},{"key":"R25","unstructured":"Lane HW and Smith SM. Nutrition in space. In: Modern Nutrition in Health and Disease, edited by Shils M, Shike M, Olson J, and Ross AC. New York: Lippincott Williams & Wilkins, 1999, p. 783\u2013788."},{"key":"R26","doi-asserted-by":"publisher","DOI":"10.1007\/BF00580849"},{"key":"R27","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1996.81.1.105"},{"key":"R28","doi-asserted-by":"publisher","DOI":"10.1161\/01.CIR.96.2.517"},{"key":"R29","doi-asserted-by":"publisher","DOI":"10.1161\/01.CIR.79.1.107"},{"key":"R30","unstructured":"Maass H, Transmontano J, and Baisch F. Response of adrenergic receptors to 10 days head-down tilt bedrest. Acta Physiol Scand 144: 61\u201368, 1992."},{"key":"R31","doi-asserted-by":"publisher","DOI":"10.1097\/00006842-200111000-00003"},{"key":"R32","doi-asserted-by":"publisher","DOI":"10.1152\/ajpheart.00740.2003"},{"key":"R33","doi-asserted-by":"publisher","DOI":"10.1097\/00004872-198604000-00012"},{"key":"R34","doi-asserted-by":"publisher","DOI":"10.1046\/j.1365-2281.2001.00315.x"},{"key":"R35","doi-asserted-by":"publisher","DOI":"10.1152\/ajpheart.1999.277.6.H2272"},{"key":"R36","doi-asserted-by":"publisher","DOI":"10.1016\/S0006-291X(80)80044-1"},{"key":"R37","doi-asserted-by":"publisher","DOI":"10.1152\/ajpheart.1989.257.5.H1389"},{"key":"R38","doi-asserted-by":"publisher","DOI":"10.1152\/ajpheart.2001.280.5.H2230"},{"key":"R39","doi-asserted-by":"publisher","DOI":"10.1161\/01.CIR.103.14.1851"},{"key":"R40","doi-asserted-by":"publisher","DOI":"10.1097\/00006842-199707000-00015"},{"key":"R41","unstructured":"Platts SH, Ziegler MG, Waters WW, Mitchell BM, and Meck JV. Midodrine prescribed to improve recurrent post-spaceflight orthostatic hypotension. Aviat Space Environ Med 75: 554\u2013556, 2004."},{"key":"R42","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1989.66.6.2778"},{"key":"R43","unstructured":"Rowell LB. Neural-humoral adjustments to orthostasis and long-term control. In: Human Cardiovascular Control. New York: Oxford University Press, 1993, p. 81\u2013117."},{"key":"R44","unstructured":"Rowell LB. Orthostatic intolerance. In: Human Cardiovascular Control. New York: Oxford University Press, 1993, p. 118\u2013161."},{"key":"R45","unstructured":"Rowell LB. Reflex control during orthostasis. In: Human Cardiovascular Control. New York: Oxford University Press, 1993, p. 37\u201380."},{"key":"R46","doi-asserted-by":"publisher","DOI":"10.1016\/S0001-2998(75)80033-X"},{"key":"R47","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1998.84.2.612"},{"key":"R48","doi-asserted-by":"publisher","DOI":"10.1152\/ajpregu.1999.277.4.R1084"},{"key":"R49","doi-asserted-by":"publisher","DOI":"10.1152\/ajpheart.1998.274.6.H1875"},{"key":"R50","unstructured":"Tan SY, Noth R, and Mulrow PJ. Direct non-chromatographic radioimmunoassay of aldosterone: validation of a commercially available kit and observations on age-related changes in concentrations in plasma. Clin Chem 24: 1531\u20131533, 1978."},{"key":"R51","doi-asserted-by":"publisher","DOI":"10.1007\/BF03350152"},{"key":"R52","doi-asserted-by":"publisher","DOI":"10.1080\/00365519109091106"},{"key":"R53","doi-asserted-by":"publisher","DOI":"10.1016\/0094-5765(94)90133-3"},{"key":"R54","doi-asserted-by":"publisher","DOI":"10.1152\/ajpendo.1993.265.1.E153"},{"key":"R55","doi-asserted-by":"publisher","DOI":"10.1152\/japplphysiol.00544.2001"},{"key":"R56","unstructured":"Ziegler MG, Woodson LC, and Kennedy B. Radioenzymatic assay of catecholamines, metabolites, and related enzymes. In: Quantitative Analysis of Catecholamines and Related Compounds, edited by Krstulovic AM. Chichester, UK: Ellis Horwood, 1986, p. 263\u2013280."},{"key":"R57","doi-asserted-by":"publisher","DOI":"10.1172\/JCI107121"}],"container-title":["American Journal of Physiology-Heart and Circulatory Physiology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.physiology.org\/doi\/pdf\/10.1152\/ajpheart.00220.2004","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2019,9,8]],"date-time":"2019-09-08T19:53:47Z","timestamp":1567972427000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.physiology.org\/doi\/10.1152\/ajpheart.00220.2004"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2005,2]]},"references-count":57,"journal-issue":{"issue":"2","published-print":{"date-parts":[[2005,2]]}},"alternative-id":["10.1152\/ajpheart.00220.2004"],"URL":"https:\/\/doi.org\/10.1152\/ajpheart.00220.2004","relation":{},"ISSN":["0363-6135","1522-1539"],"issn-type":[{"value":"0363-6135","type":"print"},{"value":"1522-1539","type":"electronic"}],"subject":[],"published":{"date-parts":[[2005,2]]}}}