Abstract
Methods: Experimental data were obtained from five chronically instrumented rhesus monkeys exposed to 96 h of 10° head-down bed rest (HDBR) and another 96 h of 80° upright control separated by 9 d of ambulatory recovery in a counter-balanced, crossover experiment design to test the hypotheses that: 1) headward and footward fluid shifts would increase systemic arterial (Eart) and left ventricular end-systolic (Ees) elastances; and 2) changes in Eart and Ees would be related in magnitude and direction. Ees and Eart were calculated from measurements taken during five observation periods for initial 2-h and 4-d exposures to HDBR that produced headward volume shifts, and acute exposure to graded levels of lower body negative pressure (LBNP) designed to produce orthostatic volume shifts. Results: There was no effect of HDBR on Ees and Eart for any observation period (initial 2-h, 4-d, of LBNP). Eart increased in a similar pattern during the 4-d exposure to both control and HDBR. Ees increased with increasing LBNP levels for both control and HDBR while Eart remained unchanged. Conclusion: Our data are consistent with the notion that elevated Eart may represent an adaptation to physical inactivity that is associated with cardiovascular deconditioning.
Original language | English (US) |
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Pages (from-to) | 7-15 |
Number of pages | 9 |
Journal | Aviation Space and Environmental Medicine |
Volume | 75 |
Issue number | 1 |
State | Published - Jan 1 2004 |
Keywords
- Arterial elastance
- Bed rest
- Lower body negative pressure
- Ventricular elastance
ASJC Scopus subject areas
- Public Health, Environmental and Occupational Health
- Pollution
- Medicine(all)