IMPACT OF ALTERED GRAVITY ON ASPECTS OF CELL BIOLOGY

This chapter summarizes the progress that has been made in determining and understanding the effect of gravity on cell function. It describes the results from three general areas of spaceflight research, and within each area, focuses on specific cell systems for which sufficient data have been accumulated. Included are (1) cell physiology, with a focus on immune cell activation; (2) cell development, with a focus on plant cell differentiation; and (3) the physiology of unicellular organisms. In addition, the chapter describes the underlying principles that govern spaceflight research on the cell, and examines experimental approaches used to investigate the effects of altered gravity on cell function. One environmental factor that has remained constant throughout evolution is the force of earth's gravitational field. The cardiovascular system counteracts gravity when it pumps blood to the upper body, but also uses the pull of gravity when it distributes fluid to the lower extremities. These well-known adaptations to gravity become clearly evident during manned orbital spaceflight, where the inertial acceleration caused by gravitational force is virtually canceled and the gravity vector is no longer detectable. In this microgravity environment, where mass is nearly weightless, astronauts experience space motion sickness, muscle atrophy and bone demineralization, as well as cardiovascular deconditioning and the redistribution and pooling of body fluids in the upper body. © 1994, Academic Press Inc.