title: Mechanism of spaceflight-induced changes in left ventricular mass.
abstract: Decrements in left ventricular (LV) mass observed after microgravity exposure have been previously postulated to be a central component of spaceflight-induced cardiovascular deconditioning. In this study, echocardiographic measurements of LV mass in astronauts demonstrated a comparative 9.1% reduction in postflight LV mass that returned to preflight values by the third day of recovery. A ground-based study in normal subjects determined that these pre- to postflight LV mass changes could be reproduced by simple dehydration. Reductions in LV mass observed immediately after spaceflight may be secondary to simple physiologic fluid exchanges.
authors.affiliation: Department of Emergency Medicine, University of Mississippi Medical Center, Jackson, Mississippi 39216, USA. rsummers@pol.net
authors.forename: Richard L
authors.initials: RL
authors.lastname: Summers
authors.forename: David S
authors.initials: DS
authors.lastname: Martin
authors.forename: Janice V
authors.initials: JV
authors.lastname: Meck
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Coleman
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D003681:Dehydration / Q000150:complications; D004452:Echocardiography; D005260:Female; D006801:Humans; D020896:Hypovolemia / Q000209:etiology; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013026:Space Flight; D013997:Time Factors; D020257:Ventricular Remodeling / Q000502:physiology*; D014893:Weightlessness / Q000009:adverse effects*