the effects of microgravity, were compared to those obtained in smooth muscle cells from rats
injected with a chemical agent directed against the RyR1 protein. In both conditions, calcium
release was significantly decreased. In contrast, in spontaneous hypertensive rats, an increase
in RyR1 expression was observed as well as the calcium-induced calcium release mechanism.
Taken together, these results show that myocytes were directly sensitive to gravity level and
that they adapt their calcium signaling pathways to vascular pressure by the regulation of the
RyR1 expression.
Effect of spaceflight on macrophase differentiation and activation
This study involved the analysis of bone marrow cells from the CB<T-2 payload following a 13-
day flight on the space shuttle to determine how spaceflight affected differentiation of cells in
the granulocytic lineage (important white blood cells produced in the bone marrow). The bone
marrow cells were isolated from the humerii (long bones of the upper limb or forelimb) of mice.
A cell counting method was utilized to assess the expression of several molecules
(Ly6C,CD11b,CD31 (PECAM-1),Ly6G (Gr-1),F4/80,CD44 and c-Fos) that defines the maturation
state of cells in the granulocytic lineage on 3 bone marrow cell subpopulations (R1, R2 and R3)
defined by their size and light scattering properties. There were no observable characteristic
differences between total bone marrow cells isolated from flight and ground-control mice.
Nevertheless, there were subpopulation differences observed that suggests neutrophil
activation in response to landing. Decreases were noticed in Ly6C, c-Fos, CD44high and Ly6G.
An increase in F4/80 suggested that the cells in the bone marrow R3 subpopulation of the mice
flown on the shuttle were more differentiated compared to the ground-controls. A loss in body
weight was also noticed in the mice that flew in space that suggest that they were subjected to
chronic stress beyond what was endured on landing. Therefore, it is not unreasonable to
suggest that there are significant changes in bone marrow phenotype in response to the stress
of the spaceflight experience (Ortega 2008).
The effects of spaceflight on stress and immunity
Understanding lymphocyte activity associated with spaceflight stressors is important in
determining the impact on associated cancer risk. This study examined the T-lymphocytes in
C57BL/6 mice (a traditional inbred strain of lab mice) after the return from a 13-day space
shuttle mission. Flight mice (FLT) and ground controls similarly housed in Animal Enclosure
Modules (AEMs) were evaluated within 3 to 5 hours after landing. Muscle strength testing and
nuclear magnetic resonance body composition measurements were performed on the mice.
After euthanasia (painlessly put to death), spleen and thymus samples were analyzed. DNA
synthesis in splenocytes (any one of the different white blood cell types situated in the spleen)
from FLT mice was low in response to phytohemagglutinin (PHA-plant chemical used to
stimulate the multiplication of white blood cells, specifically T cells) compared to AEM controls.
There was a lower percentage of T cells and higher percentage of natural killer (NK) cells (both
of which are involved in attacking tumor cells), in the FLT mice, but the percentage of B cells
(involved in producing antibodies) were similar to AEM controls. The secretion capacity of 4
cytokines (small secreted proteins that serve to regulate the immune system) in response to
activation via signaling molecules, similarly to what occurs in the body, was significantly
different in the FLT mice compared with the AEM controls. Cancer-related gene expression