This subproject is one of many research subprojects utilizing theresources provided by a Center grant funded by NIH/NCRR. The subproject andinvestigator (PI) may have received primary funding from another NIH source,and thus could be represented in other CRISP entries. The institution listed isfor the Center, which is not necessarily the institution for the investigator.Exposure to microgravity (i.e. spaceflight) results in several changes in cardiovascular function that include elevated venous compliance and heart rate, lowered blood volume, central venous pressure and stroke volume, cardiac atrophy and attenuated baroreflex function (Frey 1987; Convertino and Hoffler 1992; Fritsch et al. 1992; Fritsch-Yelle et al. 1994; Convertino and Sandler 1995). These cardiovascular adaptations are not functionally apparent during spaceflight, but become dysfunctional for the astronauts upon return to a 1G environment, manifested as orthostatic intolerance (unable to stand continuously for 10 minutes) and up to a 25% reduction in maximal exercise capacity (Convertino and Hoffler 1992; Convertino 1992; Convertino 1994). Similar cardiovascular deconditioning is also observed during prolonged 6-degree head-down bed rest (i.e. simulated microgravity) (Convertino 1990; Crandall et al. 1994; Goldstein et al. 1995; Zhang et al. 2001). A variety of countermeasures have been developed, including saline 'loading', intermittent venous pooling (lower body negative pressure; LBNP), pharmacological manipulations and resistance training, but have had only limited success (Convertino and Hoffler, 1992).
Showing the most recent 10 out of 1825 publications
