[thedoc (OP)]

Marcus Andrade asked the Naked Scientists:
   Chis Congrats for great show.  Now my question: 
When Astronauts are in orbit for prolonged periods they lose bone calcium.  Does it also reverse artery hardening?  Do astronauts produce less testosterone?  Could micro gravity be a therapy for artery hardening? Thanks
What do you think?

[evan_au]

There is increasing evidence today that the arterial cells showing calcification start to express gene pathways found in bone cells.
eg see http://circ.ahajournals.org/content/117/22/2938.full

Bone structure is continually tuned through life to adapt to the stresses on the bone; it is a dynamic balance between continual bone construction and destruction. In space, there are almost no stresses on bone (without a vigorous exercise regimen), and so bone degradation wins.

The pressure in the aorta comes from the heart pumping blood. So unless there is a significant reduction in blood pressure in space, there will still be the regular stress on the walls of the aorta, and this calcification might remain.

Astronauts are selected for being in top physical condition (hardened arteries could be a risk for the mission). But maybe they should send some astronauts who are past their "use-by" date to check it out?

[exothermic]

Prolonged weightlessness shouldn't affect atherosclerotic plaque deposition by any appreciable degree.

[exothermic]

maybe they should send some astronauts who are past their "use-by" date to check it out?

At the expense of an even further net decrease in bone density? They'll need handicapped stickers & wheelchairs on the space shuttle for that trip!

[chris]

At the British Cardiovascular Society 2017 meeting I interviewed Dr Ben Levine, who works on space physiology and vascular disease prediction in astronauts.

The above is a link to the transcript of that interview in which he discusses some of the factors mentioned in this thread.