Functional weightlessness during clinorotation of cell suspensions.

A clinostat is a device often used in gravitational biology studies. Selecting an appropriate speed of rotation, however, is a frequently debated topic, particularly for suspended cells. In an attempt to define the necessary criteria for determining an acceptable revolution speed, the primary forces governing particle behavior during clinorotation--gravity, diffusion and centrifugation--were mathematically assessed. In support of the theoretical exercise, bacterial growth experiments indicated that results obtained using a clinostat followed trends resembling previous space flight results. It is suspected that this is due, in part at least, to similarly altered external transport processes in each environment.